Aiming at the difficulty in designing weight coefficients, and the problems of large steady-state torque and flux ripple in permanent magnet synchronous motor (PMSM) model predictive torque control (MPTC) systems, a weightless model predictive torque control method based on duty cycle optimization is proposed. Firstly, a PMSM weightless MPTC is established, and interaction errors are calculated based on the defined evaluation term within each control cycle. The voltage vector corresponding to the minimum interaction error is the optimal vector, thus eliminating the weight coefficient design. Then, on the basis of the weightless MPTC, a duty cycle optimization link is introduced. The proposed duty cycle calculation method used comprehensively considers the factors of flux and torque, which can effectively suppress torque and flux ripple. The simulation results show that the performance of the proposed weightless model predictive torque control system based on duty cycle optimization is good.