Traditional angle measurement methods (laser interferometer angle measurement, autocollimator angle measurement, etc.) cannot measure the dynamic angle of the entire circumference of the measured object in real-time. Therefore, a dynamic angle measurement and compensation method for circular gratings is proposed, which uses a laser gyro goniometer to measure the dynamic angle of the circular grating in real time. Firstly, the turntable is calibrated using a self-calibration algorithm, and then the accuracy of the turntable after calibration is verified to be 7.8 ″ using an autocollimator. Secondly, the laser gyro goniometer and the reading head are synchronously triggered by a synchronous trigger plate, analyze the angular position accuracy of the turntable measured by the laser gyro goniometer at different rotational speeds, find out the rotational speed with the smallest angle error measured by the laser gyro goniometer, and finally use the harmonic analysis method to compensate for the angle error at this rotational speed. The experimental results show that the accuracy of the dynamic angle measurement system of the circular grating angle measurement system is improved from 8 “before compensation to 0.7”.