Abstract: Using mixed programming of VC++ and Matlab, a simulation system of ultrasonic phased array imaging was developed. Simulation system composed of three modules, probe module set the probe parameters and can be used to analyze its sound pressure and directivity. Defect module simulates defects and choose defects imaging method. Simulation imaging module completes ultrasonic waves transmitted by the probe, propagating in the workpiece and generating echo signals through interaction with defects, then echo signals received by the probe, finally after series of signal processing, including envelope extraction, logarithmic compression, DSC transform and so on, showed graphically.