Micro-photoluminescence (μ-PL) mapping with the spatial resolution of micrometer was performed on a CdZnTe(CZT) wafer to study its characteristics of the sub-micrometer layer under the surface. Two scales of mapping on micrometer over the defect-containing region and on millimeter over the large area were employed. Each acquired PL spectrum was fitted based on a physical model. Statistical results of the fitting parameters of effective temperature Te show two centers for the temperature distribution, implying two mechanisms for the PL processes. The inhomogeneity for the luminescent points was also shown by the statistics. The maps of Te directly give the temperature position of each PL points. Similar μ-PL mapping was carried out after Br polishing on the sample surface. The fitting results show a good improvement on the homogeneity of Te. The two different defects on the Te map after polishing show different behavior, suggesting different origins for them. The statistics and the map of Te in μ-PL mapping on the scale of millimeter over large area demonstrate the general properties of the CZT wafer.