The ultrasonic detection method has the advantages of high sensitivity, strong penetration and wide range of applications, and has become the main technical direction of nondestructive testing of composite material structures. In response to the urgent need of detecting the delamination defects of carbon fiber composite wheel hub, an ultrasonic detection system of carbon fiber composite wheel hub is fabricated to detect the delamination defects of carbon fiber composite wheel hub based on the analysis of the principle of ultrasonic flaw detection. The experimental results show that the system can effectively detect the delamination defects of carbon fiber composite wheel hub. It is simple in structure, convenient in installation and debugging, low in cost and easy to operate. It can meet the needs of engineering practice.