Tens of Cd0.9Zn0.1 Te wafers from three ingots grown by the vertical Bridgman method (VBM) are characterized by infrared (IR) transmission. Four types of distinct IR transmission spectra are found for these wafers. Each of them corresponds to one kind of wafers with specified qualities. At the same time, approximate mathematical relations exist between the wafer dislocation density and their IR transmissions at the wavenumber 4000 cm-1, as well as between the resistivity and the IR transmissions at the wavenumber 500cm-1. The reasons of the above results are attempted to be given.