The rotor angle of permanent magnet motor has an important influence on the control of the motor. At present, the resolver is widely used in the permanent magnet traction motor to detect the rotor angle and speed information. Based on the TMS320F28377D dual-core CPU combined with AD2S1210 decoding chip, a rotor position detection system is formed. Angle segment compensation is used for error correction. Thus, the accurate rotor angle information is provided for the permanent magnet motor control algorithm. The rotor angle information output by the decoding chip under different rotor frequencies is verified by the hardware-in-the-loop simulation platform. The detection method has the characteristics of high precision and strong anti-interference ability. It can meet the requirements of high reliability and stability of the traction system. The results of the simulation and experiments show the feasibility and effectiveness of the angle detection method proposed.