Aiming at the problem of weighting factor design and adjustment of model predictive torque control (MPTC) of permanent magnet synchronous motor (PMSM), the pre-unit cost function is used to transfer the control objects into dimensionless variables, so as to eliminate the weighting factor, and its effectiveness is verified by simulation. Studies show that the pre-unit cost function unifies the range of control objects, and it can only be used in the area where the importance of all control objects is almost the same, and its computational load is large, and its real-time performance of the algorithm is reduced.