The electromagnetic torque of permanent magnet synchronous motor (PMSM) affects the power distribution precision in the electro-mechanical transmission (EMT). This paper proposes a torque observers for PMSM. Based on the mathematic model of the motor, command torque and the measured rotor speed, we can observe the actual torque precisely, moreover, the power of electric path is more accurate. The observer can be used as the reference power flow distribution, which is an effective way for the precise control of power flow. The performances of the observer are verified by simulation.