The Hemispherical resonator gyro is a new kind of vibratory gyro with high precision and long life. In order to design a hemispherical resonator gyro with good angular rate measurement accuracy and low noise characteristics, and to meet the requirements of accurate orientation and attitude control of the spacecraft, the mechanism of noise generation of hemispherical resonator gyro is analyzed in this paper, and the effects of the harmonic oscillator parameters, control system parameters and electronic circuit parameters on the noise of the hemispherical gyro are discussed, the optimized design of the sensor and electronic circuit is carried out. The results show that the noise level and angular random walk after the optimized design are significantly reduced by about 50% of that before the optimized design, which is comparable to the noise level of the basic type HRG130P hemispherical resonator gyro from Northrop Grumman Corporation in U.S.A.