Abstract: The force-balanced gyro which driving by electromagnetic force, and detecting by capacitance has prominent advantages of higher sensitivity and higher precision than other Mems gyros.But its interface circuit is comparative complex.Its interface circuit includes two parts, which are driving circuit and detecting circuit.The main function of driving circuit is producing a stable sinusoidal vibration under its natural frequency of driving modal for the gyro.The function of detecting circuit is pick up the angular velocity signal created by the gyro.We have adopted force-balanced system to increase the working band-width and linearity of the gyro.Here we analyzed the principle of transfer-function and stability of this Memms gyro.We have also introduced several main devices which had been used in this interface circuit.