Disclosed are a method, a device and a system for improving system accuracy of an X-Y motion platform, and the method includes: taking a picture of a preset calibration board synchronously as a controlled equipment on an X-Y motion platform moves, and analyzing the picture to obtain pixel coordinates of a calibration point in the picture, where the preset calibration board is taken as a reference; acquiring actual coordinates of the calibration point on the calibration board, and calculating actual position coordinates of the controlled equipment on the X-Y motion platform from the actual coordinates and the pixel coordinates of the calibration point; and adjusting a motion control system of the X-Y motion platform according to the actual position coordinates, to control the motion of the X-Y motion platform to perform motion compensation for the controlled equipment. With the technical solution of the invention, the system accuracy can be improved, and the requirements for assembly and device selection can be reduced.