The invention provides a permanent-magnet synchronous electrical machine torque control method. When an electrical machine is in a low speed segment, an open loop torque control method is employed to control electrical machine torque, and a corresponding relation between given torque and Q axis currents is obtained via a calibration method and fitted into a curve; the Q axis currents can be directly obtained based on the given torque; when the electrical machine is in a high speed and low intensity magnetic zone, a closed loop torque control method is adopted for estimating output power of a controller via D and Q axis currents and voltage, the output power divided by electrical machine rotating speed is feedback torque, a PI regulator is formed between the feedback torque and the given torque, and output value of the PI regulator is a given Q axis current. The method is not dependent on nominal parameters of the electrical machine; based on operation work conditions of the electrical machine, D and Q axis currents and voltage of the electrical machine can be collected in real time, the output power of the electrical machine controller can be estimated, and a problem that essential electrical machine parameters cannot be accurately reflected via inductance parameters in rated working conditions can be prevented. Via the method, the collected D and Q axis voltage is subjected to time-delay compensation and dead zone compensation, accurate D and Q axis voltage can be obtained, and accurate power estimation can be realized.