Abstract: When spacecraft moves in the orbit using FOG navigation system, the performance of inertia instrument will fall off after experiencing a long and complicated environment. The power of light source falls off is a kind of fault mode. This mode will induce FOG's bandwidth to decline and the navigation precision will descend when spacecraft transfers to the other orbit or moves to a bigger angle. To resolve this problem, a method to compensate FOG's bandwidth using particle swarm optimization algorithm was brought forward. With this method a dynamic compensator could be realized without knowing the dynamic characteristics of FOG. The parameter of the compensator was optimized according to the measurement data of FOG and the reference model. But sometimes this method ran into local optimization easily. To increase this algorithm's performance, simulated annealing algorithm was induced to avoid local optimization. Finally, dynamic navigation experiment of FOG navigation system show that this algorithm is effective. This method can increase navigation precision when spacecraft moves to a bigger angle and possess a better engineering value.