to compensate the drift caused by changes of temperature we should first judge whether the drift is produced. From the above analysis of the modulation principle of the Y waveguides, we can detect whether drift comes out and its number by detecting the square wave of the interference signal in positive and negative spheres output during the reset period. Meanwhile, in the control process of the digital closed-loop, as temporary angular velocity can increase the scope of the interference signal, thereby influence the detection of the drift information of the modulate degree, thus after detecting the interference signal of reset period, and minus the signal of neighbor signal from it, then the impact of Instantaneous angular acceleration on drift detection can be removed.