The AC motor is simple in structure, easy in manufacture, low in cost, easy to control. It is gradually replacing the DC motor in many cases and becoming the first choice for motor users. However, the speed regulation system of AC motor is very complex. It is difficult to match DC motor. This paper designs an AC motor control system based on the ARM platform which makes use of Vector control and PID algorithm to control the AC motor exactly. The system has three parts:hardware, software, and the interface of the host computer. The hardware circuit includes current acquisition and IGBT circuit. The software part uses C language and KEI MDK software development tools to program. The upper computer uses the LabVIEW software to write the test interface and runs the PID program. Finally we develop a set of motor control for AC motor speed control system.