The influence on the low-defect surface of GaSb thin-film material by the ratio of Sb to Ga (V/III) along with the reducing of the growth temperature was investigated systematically. In order to obtain a good surface morphology of the GaSb epitaxial layer with low defect, both of the growth temperature and the V/III ratio should be reduced at the same time. The optimal growth conditions of Low-temperature GaSb thin films are that the growth temperature is Tc+60℃ and the V/III ratio is about 7.1 when Sb cracker temperature is 900℃.