Abstract: With the development of modern technology, people have increasingly higher requirements for the levelness accuracy of various base platforms. However, existing optical quadrant instruments can no longer fully meet the requirements for detecting the levelness of base platforms, especially for base platforms on some ships (such as military vessels), where the levelness accuracy requirements are very high. This paper introduces the working principle and calculation method of measuring platform tilt using a gravity sensor. Taking the mathematical model for solving the levelness error of a ship when it is anchored as an example, it analyzes the influence of the ship's pitch and roll on levelness measurement, thereby illustrating the measurement and calculation method of the gravity sensor levelness measuring instrument. Keywords: levelness; gravity sensor; pitch and roll; tilt error Abstract: With the development of modern science, all kinds of pedestal platforms must be more precise. However, in the gradienter checking, the capability of the current optics quadrant instruments cannot adapt to some of the pedestal platforms entirely, especially to some pedestal platforms on the ships (such as: naval ships). Firstly, the principle and the calculation method of the gravity accelerometer were introduced in this article. Then, an example based on the error computational model of the platform's gradienter checking was introduced in detail in order to analyze the effect of the ship's vibration in plat's gradienter checking. Key words: gradienter; gravity sensor; pitch and roll; tilt error I. Overview Modern equipment has high requirements for the levelness accuracy of some specific systems on the platform, so accurate measurement of the levelness of each platform is crucial[1]. Traditional inspection and regulation uses an optical quadrant to detect the level of the platform, which is done by manual reading. The detection method is cumbersome, the reading is difficult, and the accuracy is hard to guarantee. Moreover, the optical quadrant can only give the tilt angle of the tilted platform after multiple multi-directional measurements [2]. This is a fatal weakness in the case of detecting the platform or controlling the level in real time. However, the gravity sensor level measuring instrument can achieve a measurement accuracy of 0.002 radians. It can also obtain the plane angle between the platform and the reference plane and the direction of the plane angle by pre-programming and multiple sensors measuring different directions of the platform. This measurement method greatly facilitates the adjustment of the platform plane. The article details the principle of using gravity sensor to measure level and uses the influence of ship pitch and roll on the platform level measurement as an example to illustrate the measurement method. For details, please click: Principle Analysis of Gravity Sensor Level Measuring Instrument