The invention relates to a digital closed loop servo circuit applied to a quartz flexible accelerometer, which comprises a differential capacitor detection circuit, a triangular wave generating circuit, a pre-filtering amplifying circuit, an A/D conversion circuit, a D/A conversion circuit, a drive amplifying circuit and a digital signal processing circuit, wherein the triangular wave generating circuit is connected with the input end of the differential capacitor detection circuit, the differential capacitor detection circuit is connected with a differential capacitor of a meter mechanical part of the quartz flexible accelerometer, the differential capacitor detection circuit is connected with the pre-filtering amplifying circuit, the pre-filtering amplifying circuit is connected with the A/D conversion circuit, the digital signal processing circuit is connected with the A/D conversion circuit, the digital quantity output by the digital signal processing circuit is connected with a navigation computer through an output end and is connected with the D/A conversion circuit through the output end at the same time, the D/A conversion circuit is connected with the drive amplifying circuit, and a current signal output by the drive amplifying circuit is connected with a torque coil of the meter mechanical part of the quartz flexible accelerometer through the output end of the drive amplifying circuit.