The liquid encapsulated Czochralski (LEC) method is used to study the growth of GaSb single crystal, the effects of growth control under the two kinds of liquid sealing agent of equal molar ratio (LiCl+KCl) and B2O3 are also compared in this paper. It is clear that how the insulation cover improve the gradient of the system temperature field, and then analyze the impact of temperature field on the crystal growth. The test results from the single crystal region shows the distribution of dislocations within the crystal, XRD test results indicate the quality of the single region is also higher.