Infrared photo-thermal absorption effect was used extensively in detecting the micro-defects in semiconductor materials (silicon wafers) as a nondestructive and non-contact technology. This effect was adopted initially to detect the structural characteristic of the defects in CdZnTe (CZT) crystal and images with obvious coherent fringes were obtained, which were investigated systemically. It was confirmed that the coherent fringes of the Infrared photo-thermal absorption images of CZT wafers come from the interference of incident light relative to parameters of incident light, wafer thickness, thermal conductivity and band gap of materials. Finally, the micro-defects of CZT materials and their distribution along depth direction were obtained by optimizing the test conditions.