Abstract: This is the simulation of eddy current array test sheet crack through CIVA software, waveform length information through airspace transverse cracking implied transverse crack length is calculated. The C scan diagram can directly reflect the qualitative defect location. Based on the space wave of the induced voltage, it was analyzed that the waveform width comprised the information of the crack length. The relationship between the crack length and the waveform width was established using the least squares method, and the crack length error between the calculation and the true was analyzed. The studing results showed that crack length relative to it corresponding space waveform width, it space waveform width inceasing with the length of crack adding; Longitudinal axis,s space waveform width do not increasing with the crack's length adding, so information of crack depth without space waveform width;and last the change of crack width can not increasing the changing of the waveform space width.