The error of resolver decoding circuit has effect on the rotor position detection accuracy of permanent magnet synchronous motor (PMSM). In order to reduce the influence, the principle of decoding circuit is analyzed. A decoding circuit with the advantages of high precision and fast response is proposed. The low voltage operational amplifier MCA33202 is used to decode the sine and cosine signals from the resolver, and the unit feedback closed-loop system is constructed based on the estimated angle after decoding. The key device parameters of the decoding circuit are optimized and the rotor position detection accuracy of PMSM is increased by the proposed method. Finally, the effectiveness and feasibility of the decoding circuit are verified by a 2.5 kW high-speed PMSM.