Abstract: Pulsed eddy current(PEC) testing technology is a newly developed electromagnetic nondestructive testing technology, with its penetration depth and the sensitivity having a close relationship with excitation parameters, and therefore appropriate excitation parameters are very necessary. The finite model of circular probe using COMSOL is built on subsurface defect with different peak of excitation, different duty cycle of excitation and the same integral of amplitude on the time. After simulation, increasing the peak of excitation can get better sensibility and the duty cycle can decide the penetration depth through data analysis of Matlab. The conclusion will provide some references on subsurface defect detection.