Preparation method and the important application background of ZnSe crystal were introduced. Various defects produced in the preparation of ZnSe by chemical vapor deposition (CVD), including haze, hole and microcrack, inclusion, layer and cellular, were summarized systematically. The defects were characterized by SEM, stereoscopic microscope, metallographic microscope and Fourier spectrometer. Based on domestic and foreign literatures and the analysis by our ourselves, the possible mechanism and inhibition methods of various defects were expounded and analyzed.