The microstructure and tensile properties in the conditions of room-temperature and high-temperature, and the reasons of fracture morphology and porosity formation in high temperature tensile fracture about TC4 titanium alloy formend by selective laser melting have been investigated. The results show that the room temperature tensile properties of the TC4 alloy without heat treatment characterized by high strength and low shaping. After the 800 ℃,4h vacuum annealing, the properties of TC4 alloy reached the level of forging pieces of the same brand. Under the tensile conditions at 400 ℃,500 ℃,600 ℃, strength of the deposited samples is higher than that of annealed samples on average of 24.7%,27.9%,8.3%. But the elongation of the deposited samples is lower, excepting the average elongation achieved 45.5% under 600 ℃ for the deposited samples, which has been nearly twice comparing with the annealed sample. Numerous densely distributed pores existed at the fracture place about annealed samples employing by high-temperature tensile. The pores were first formed at grain boundaries, and then in the process of high temperature tensile deformation, due to the necking deformation of the sample, the pores accumulated to the fracture site along with the deformation.