Abstract: As-grown Cd_0.9Zn_0.1Te wafer prepared by vertical Bridgman method was annealed using Cd_1-yZn_y alloy as source. It is found that after annealing, the concentration deviation of Zn in the radial direction decreases from 0.15at%to 0.05at%, the impurity contaminations of Al, Na, Mg and Cu are reduced to some degree, the full width at half maximum （FWHM） which indicates the crystallinity fells from 182″to 53″, the IR transmittance increases from 56.6%to 62.1%and the resistance elevates from 7.25×10⁸Ωcm to 2.5×10¹⁰Ωcm. These changes indicate that the annealing treatment can upgrade the performance of high resistance CdZnTe in the proper circumstances.