In Fiber Optic Gyroscope (FOG) system, one of the most important parts in full closed-loop control is 2π reposition modulation. Due to the increase of half voltage of miniaturized multi-functional integrated optic chip, the modulation signal in miniaturized fiber optic gyroscope can’t afford to the full range voltage of 2π. Based on the analysis of closed-loop principle, a new method was presented, which was called symmetrical reposition modulation, and the method can be well used to achieve the reposition modulation in closed-loop control to miniaturized fiber optic gyroscope.