Abstract : The linkage mechanism is an important working device of underground loaders, and its design quality and dynamic characteristics directly affect the productivity and working performance of the whole machine. This paper establishes a dynamic model of the six-link linkage of an underground loader's linkage mechanism for the digging and lifting processes using the Lagrange principle. The relationship between the initial position angle of the linkage and the torque output by the hydraulic cylinder is obtained, and a corresponding module diagram is built in MATLAB/Simulink, providing a basis for determining its design parameters and laying the foundation for the dynamic simulation and dynamic performance research of the linkage mechanism of underground loaders. Keywords : underground loader; linkage mechanism; dynamic model; MATLAB/Simulink; 1 Introduction As an important working device of an underground loader (LHD unit), the linkage mechanism completes multiple actions such as digging, lifting, and unloading. Due to its complex working process, the dynamic study of the linkage mechanism is particularly important. To study the dynamics of the linkage mechanism, it is necessary to first establish its dynamic model. Currently, most studies on the linkage mechanism of underground loaders use three-dimensional software solid modeling, which is then imported into ADAMS for dynamic analysis. This method has problems such as a relatively long model establishment cycle and complex research. However, using Simulink for modeling is simpler, more efficient, accurate, and faster than the usual methods for solving mechanism dynamics, and it can conveniently and quickly provide dynamic simulation curves. Therefore, this paper establishes a Lagrangian dynamic mathematical model of the linkage mechanism, imports it into the MATLAB/Simulink toolbox, and establishes a simulation model of the relationship between the rotation angle of the linkage mechanism and the torque provided by the bucket hydraulic cylinder and the lifting hydraulic cylinder in the two main working processes of the loader's digging and lifting operations. This creates conditions for further analysis and research on the dynamic performance of the linkage mechanism. 2. Establishment of a Six-Bar Linkage Dynamic Model During the operation of the loader, the linkage mechanism experiences the greatest force mainly during the digging and lifting processes. Therefore, dynamic modeling of these two working processes is essential. 2.1 Establishment of a Dynamic Model for the Digging Process (Full text download of Simulink-based dynamic modeling of the loader's linkage mechanism)