To further improve the performance and stability of the primary mode for a Silicon Micro Machined gyroscope, a new driving circuit based on the self-oscillation principle and controlled by Field Programming Gate Array(FPGA) digital signal processing was proposed. Based on the characters of the digital signal processing and the principle of self-oscillation, the models for the loop phase control and oscillation amplitude control were designed and analyzed,then the control methods in which the loop phase was controlled by ‘frequency measure and adjust program’ and the signal amplitude was controlled by ‘PID control program’ were presented. Experimental results indicate that the precision of the oscillation amplitude is up to 1.5×10-5, and the driving frequency can follow the change of the primary mode resonant frequency. In addition, by introducing the digital signal control system, the thermal sensitivity of oscillation amplitude has improved from 7.69×10-5/℃ to 1.183×10-5/℃. Compared with an analog circuit, this system has more precision amplitude and better temperature adaptation.