A new method to test and analyze on measuring error of fiber-optic gyroscope（FOG） in the state of swaying by using high frequency angular vibration platform and angular rate integral method is proposed and experimentally validated. The proposed method first integrates the sensitized angular rate of the FOG to get the measured angular displacement

then subtracts the real angular displacement to obtain the accumulated angular displacement error of FOG. The changing patterns of the FOG measuring error in the state of swaying can be discovered by using th method

which can be further utilized to analyze the existing problems during FOG designing an suppress the measuring error. The proposed method makes up for the deficiency of the existing testing methods

and provides a new analyze and test method for designing and using FOG.