Abstract: Two-millimeter thick 2195 Al-Li alloy plates were welded by friction stir welding at different welding speeds (100-300 mm·min^-1). The effects of welding speed on tensile properties of the joint at room and cryogenic (-183℃) temperatures were studied. The difference in the change of tensile properties between the joint and base metal from room temperature to cryogenic temperature was also investigated. The results show that the yield strength and tensile strength of the joint at cryogenic temperature and different welding speeds were higher than those at room temperature. When the welding speed was 200 mm·min^-1, the tensile properties of the joint at room and cryogenic temperatures were the best. From room temperature to cryogenic temperature, the increase ranges of the tensile strength and ductility of the joint were higher than those of the base metal, indicating that the increase degree in tensile properties of the joint at cryogenic temperature was larger than that of the base metal. With increasing welding speed, the tesile fracture positions shifted from the near retreating side spot in the weld nugget zone to the zigzag line.