The wetting behavior of molten GaSb drops on the substrates of GaP,BN or GaAs in space has been investigated using Chinese recovered satellite.The interaction at the interface of the molten drop and the substrate has been analyzed and compared with the results on the earth.The experiment results show that the gravity has an effect on the wetting behavior of GaSb molten drop.The contact angle of GaSb drop with GaP and BN substrates in space is larger than that on the earth.The morphology of the interface between the concreted drop and the substrate indicates that on the earth the interaction at the liquid/solid interface is strong and a wider transition region exists.It is concerned that the gravity convection is of benefit to the transfer of matters.The experiment results also show that the morphology of the samples concreted in space is more uniform than that on the earth.