SP700 titanium alloy has excellent superplasticity at low temperature, the paper used fiber laser welding SP700 titanium alloy to study the superplastic forming ability, microstructure evolution and RT tensile property after SPF. Result indicates that the welding direction parallel to the rolling direction of base material could have better superplasticity to form a cone part at 800℃, the max. pressure and cone height is 0.8MPa and 75mm, respectively, which is 20mm higher than base material"s. With the increase of deformation, the coarse columnar grains and weld undercut were eliminated and the grains was comparably fine. With about 33% deformation reduction, the tensile strength of materials with two welding directions were all decreased, and tensile strength of specimen with welding direction parallel to the rolling direction and formed at 775℃ only decreased by 2.2%. The fracture position all were on the base material for the cone part and tensile specimen.