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 is 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 T_c + 60°C and the V/III ratio is about 7.1, when the Sb cracker temperature is 900°C.