Because an AC speed regulating system is abstract and complex, the study on practical teaching method based on MATLAB software is quite necessary in the AC speed regulating system course at our university. The permanent magnet synchronous motor (PMSM) vector control system is taken as an example to explain in details the practical teaching method based on MATLAB. The course content is divided into several knowledge modules based on speed regulation methods. The concept of subsystem in Simulink is introduced. Each type of speed regulating systems can be divided into several subsystems according to its functions. The control principle, system constitution and design method of each AC speed regulation system is explained by different function subsystems. The instructor vividly demonstrates the control system simulation model of AC speed regulation systems in class, and the students establish and modify the existing simulation model by themselves on the computers under the guidance of the instructor. In this way, the students' practical ability and teaching quality of specialized courses can be improved greatly.