Fiber Optic Gyro (FOG) has been widely applied in stabilization loop of electro-optical tracking and pointing system, but the time delay unit caused by signal processing and transfer delay in FOG constraints the bandwidth of stabilization loop. On the basis of comparisons among limited memory filter, Kalman filter and least square method, least square method is adopted to forecast the measurement output of FOG, which compensates its time delay unit. In light of the measurement requirement of FOG and characteristics of time delay, factors affecting compensation accuracy are analyzed, and the degree of polynomial fitting of different least square method is tested. The result shows that the time delay unit of FOG can be well compensated by using the least square method of five-point and four-degree extrapolating two points in the frequency range below 200 Hz.