Instrument calibration is a technical means to restore and maintain equipment performance indicators and ensure accurate and reliable measurements. Therefore, it needs to be calibrated regularly by nationally authorized metrology and calibration institutions. However, with the rapid development of computer technology, large-scale integrated circuit technology, and communication technology, the field of instrument technology has undergone tremendous changes, evolving from the initial analog instruments to today's digital instruments, embedded instruments, and intelligent instruments. This has injected new vitality into the field of modern measurement technology and instrument control, with new testing fields, methods, and instrument structures constantly emerging. In many aspects, it has broken through the traditional concept of instruments, and the function and role of electronic instruments have undergone a qualitative change. In this context, the relationship between instruments and testing systems has become even more important. Without the support of automatic or intelligent testing systems, some complex experiments simply cannot obtain ideal test results. The application of virtual instrument technology in the metrology and calibration work of digital multimeters in this project, namely the automatic calibration system for digital multimeters, is based on the needs of laboratory metrology work and in accordance with the requirements of current relevant verification procedures. The user interface and control program were developed using the LabVIEW software environment. This software system ensures the reliability of the calibration process and the accuracy of calibration data through automatic calibration of digital multimeters and automatic data processing. The overall system design of a complete LabVIEW program mainly consists of three parts: the front panel, the block diagram, and the icon and connector panes. The front panel is an interactive graphical user interface used to set input values ​​and observe output quantities. The block diagram is the graphical source code that defines the functions of the VIs, using a graphical language to control the control and indication quantities on the front panel. The block diagram and connector panes are used to define the program as a subroutine for calling from other programs. **General Calibration Steps:** **● Warm up the instruments (including the instrument being calibrated and the standard source);** **● Set the instrument status and record measurement data;** **● Judge the data results and provide conclusions;** **● Automatically generate calibration certificates and original records.** **This system is modularly programmed, mainly including:** **● Initialization Settings Module** **● Data Acquisition and Dynamic Display Module** **● Certificate Generation Module** ** Specific Implementation Process of the Automated Calibration System :** First, the standard source and digital multimeter are powered on and warmed up as required. Hardware devices (GPIB card, 488 cable, etc.) are connected. After the hardware connection is complete, the computer is started, and the physical address allocation of the entire test system is searched. Based on the searched instrument addresses, the correct address configuration is set during the calibration software operation. **1. Initialization Settings Module:** Double-click the corresponding automated calibration program icon to start the system and enter the main interface of the test system. The main interface is designed for simplicity and practicality, with function buttons on the left. The first module accessed is the initialization settings module. The front panel of the initialization module is shown in Figure 2. The initialization module requires setting the calibration items for the device under test, setting the GPIB addresses of the instrument and the standard source, and selecting whether it is the first test. This function is to save the measurement data to prevent data loss due to accidents, requiring retesting. Select the Chinese or English language, select calibration/verification, and select the name of the device under test. The initialization setup is then complete. 2. Data Acquisition and Dynamic Display Module. The main functions of this module include: initializing the instrument, setting the instrument status, measuring values, controlling the number of data bits, dynamically displaying data, judging data results, and saving data. The automated data acquisition process completely simulates the manual measurement process. The instrument initialization configuration, as well as modules for range, display bits, accuracy, sampling rate, sampling time, measured value, and function selection, can be downloaded from the NI website. Programmers can also write corresponding modules based on the SCPI language commands provided in the instrument programming manual. The data display bits, data range, upper and lower limits, etc., in this module are automatically generated according to the requirements of the test metrology for the instrument, and the data result judgment is also completed automatically. The program displays unqualified data in red font, making it easy for metrologists to identify these unqualified data after the measurement is completed. The front panel of the data acquisition dynamic display module is shown in Figure 3. The certificate and original record generation module automatically generates certificates and original records, greatly facilitating the work of metrologists and eliminating errors easily caused by manual operation, thus freeing up labor. Metrologists only need to input relevant instrument information, calibration information, calibration items, and select the corresponding certificate template on the front panel of the certificate generation module; the program will then automatically generate the corresponding calibration certificate and original record. The front panel of the certificate module is shown in Figure 4. Conclusion This system has been put into use in metrology departments such as the Electrical Engineering Laboratory of Aerospace Institute 514 and the Hebei Provincial Electric Power Research Institute. It has freed up labor, greatly improved calibration efficiency, and better ensured the accuracy and reliability of calibration. This system is developed based on LabVIEW, is highly operable and fast, and can simulate the manual metrology process to achieve automated testing and metrology. The system has a clear hierarchical structure, making it easy to port and update modules. It can also directly generate certificates and original records, saving manpower and material resources, offering fast measurement speeds, avoiding contact between personnel and high voltage/current, thus protecting personnel safety. Furthermore, it boasts numerous measurement data points, high accuracy and reliability, and eliminates errors that may occur in manual counting and arithmetic errors in manual calculation. Editor: He Shiping