Te inclusions are common defects in cadmium zinc telluride (CdZnTe, CZT) crystals. The objective of this study is to optimize the quality and properties of CZT crystals by improving the process parameters for growing CZT crystal by traveling heater method (THM) and designing an in-situ heating treatment to reduce the quantity and size of Te inclusions. The process parameters were optimized by considering the interactions between the crystal growth rate and temperature, the ratio of Te-rich materials and the temperature field. Based on the different solubilities of Te at different temperatures, this study selected 800 ℃ as the growth temperature and devised an in-situ heating treatment scheme comprising high-temperature dissolution and low-temperature desolvation. This scheme was designed to enhance the absorption of Te inclusions by a long annealing time at 860 ℃ and to reduce the number of large-size Te inclusions by a rapid temperature reduction. The results demonstrate that CdZnTe crystals subjected to in-situ heating treatment exhibit a notable reduction in the concentration of large-size Te inclusions, an increase in the concentration of small-size Te inclusions, a reduction in impurity defects and Tei, and an increase in the concentration of . The current-voltage characterisation tests and energy spectral response tests show that the in-situ heating treated CdZnTe crystals exhibit higher resistivity and superior energy resolution.