Abstract: With decades of development,a dynamic ring laser goniometer(DLG) becomes a kind of dynamic angle measuring system with high precision and sensitivity.The structure and principle of DLG system were introduced.In order to increase the accuracy of angle measurement and make the best use of the ring laser gyro,the major errors were analyzed qualitatively and calculated quantificationally,and the total angle measure uncertainty of the system was about 0.3''.The result shows that the quantization error will influence the accuracy of angle measurement significantly,and it's instructive to find the methods to increase the angle measuring accuracy further.