It's necessary to make ultrasonic testing on the inner defects of the workpieces which can prove the producing safety. In order to detect the inner defects of the shaft sleeve workpieces with variable cross section, the control system of an ultrasonic test was presented based on the combination of industrial control computer and motion control card. The hardware of the control system was designed and built, and test software was programmed. This system can realize the automation of the ultrasonic test of the shaft sleeve with variable section which can ensure the accuracy of the detection and increase the efficiency of testing.