The growth technology with Cd reservoir controlled is the most effective method to solve second phase defects problem in CdZnTe crystal.With numerical simulation and experimental adjustment,the controllability of the temperature of Cd reservoir in VB case and in VGF case is compared in this paper.On the basis of the temperature of Cd reservoir controlled designedly,the influences of the temperature of Cd reservoir on the size and distribution of second phase defects are researched.In VB case,the temperature of Cd reservoir decreased greatly.As a result,some tellurium triangle like defects with a size which could reach a few microns are observed in the tale of the ingot.For the ingots growth by VGF method,when the temperature of Cd reservoir is controlled in the range of 820～790℃,although the second phase defects in the top mid of the ingot is generally improved,the tale and edgy of the ingot can be greatly improved.