In order to provide the basis for the actual construction and performance optimization， the working principle and system structure of double-closed-loop resonant fiber optical gyro using acousto-optic frequency shifter are introduced in this paper， and a Simulink simulation model is established. Simulation results show that frequency locking can be completed within 18 ms， measurement range is expanded from ±0.8 rad/s to ±9 rad/s， and nonlinearity is reduced from 1.9% to 0.46%. It shows that compared with single closed-loop resonant fiber optical gyro， double closed-loop resonant fiber optical gyro using the acousto-optic frequency shifter has a larger dynamic range and lower nonlinearity of the scale factor.