To solve the problem of robust H∞ control for permanent magnet synchronous motor (PMSM), a state space model based on dq rotating coordinate system was constructed. Through static decoupling control, the strongly coupled nonlinear PMSM model was transformed into a linear system. A robust H∞ controller was designed. The solution of the controller was transformed into the feasible solution of matrix inequality, and the state information of the speed regulation process of PMSM was obtained by using the linear matrix inequality (LMI) toolbox. The simulation results showed that the PMSM system with robust controller had the advantages of fast response speed, excellent control performance and insensitive load variation, which could meet the design requirements.