Abstract: Based on the the pulse ultrasonic detecting theory, a four channel ultrasonic flaw detection system was designed. With C8051 processor as its controlling core unit, the system adopted PCI8001 to achieve high speed data acquisition. In order to implement the effective evaluation of the flaws, the software of ultrasonic non-destructive testing system was designed in VC6.0 environment. The system could realize real-time data acquisition and display of ultrasonic wave and could give an alarm automatically when the existing flaw was detected. The application proved that it was flexible and easy to use.