The amplitude controlloop of hemispherical resonator gyroscopes(HRG) is used for vibration excitation and amplitude maintenance of HRG. The scale factor of HRG working in force to rebalance (FTR)mode is proportional to the amplitude of vibration. In this paper, the working principle of HRG working in FTR mode is theoretically deduced，Then, it is analyzed that the traditional amplitude control method will change the scale factor of the hemispherical gyroscope due to the influence of external temperature change and aging of electronic components. And finally, the optimization method of HRG amplitude control is proposed, which can greatly reduce the difficulty of realizing the circuit under the condition of achieving the same scale factor stability.