To improve the overall detection performance of MEMS gyroscope, the impact of phase error in demodulated reference signal on the detection of MEMS gyroscope was analyzed, and a phase correction method based on vector inner product phase detector was proposed. Firstly, the impact of phase error on demodulation results was theoretically analyzed. Then, the simulation models of three typical MEMS gyroscope detection circuits were established, including open-loop demodulation, electrostatic feedback quadrature error cancellation plus open-loop demodulation, and electrostatic feedback quadrature error cancellation plus closed-loop demodulation, and simulation of phase error in demodulated reference signal was carried out. Results show that among the three demodulation methods, the impacts of phase error on angular velocity and quadrature error were basically the same, while those on the dynamic range of gyroscope were different. Under the same input conditions, the larger the phase error was, the more the demodulated angular velocity and quadrature error were deviated from the real value, so it is necessary to carry out phase correction to eliminate such influence. On this basis, the vector inner product phase detection method was introduced into the MEMS gyroscope detection circuit, and a general phase correction method which can be applied in three cases was proposed and simulated. Simulation results indicate that this method can eliminate phase error, calibrate quadrature error coefficient and angular velocity demodulation error, and improve the dynamic range of electrostatic feedback quadrature error cancellation plus open-loop demodulation circuit without affecting the start-up time of MEMS gyroscope, which has good versatility.