The growth process of Cd0.9Mn0.1Te crystal by vertical Bridgman method (VBM) was simulated in detail by Fluent software. A two-dimensional finite volume numerical model was established to discuss the heat transfer, flow and growth interface of the melt in the crucible. The effects of three different temperature gradient conditions (5 K / cm, 10 K / cm and 15 K / cm) on the solid-liquid interface were analyzed. The results show that under the model calculation conditions, with the increase of temperature gradient, the trend of interface concave to liquid region increases in the middle growth period, which can better suppress convection. With the crystal growth, the melt ratio will continue to decrease, the melt flow rate near the growth interface increases gradually, and the flow velocity fluctuation increases gradually. The experimental conditions were improved according to the simulation results, and CdMnTe crystals with good quality were finally grown.