In order to reveal the variation of microstructure, mechanical properties and phase composition of Ti-6Al-7Nb alloy with different heat treatment temperatures, the microstructure evolution of Ti-6Al-7Nb alloy was studied at 650°C -1030°C under air-cooled conditions, and the room temperature mechanical properties and XRD of the samples were tested. The results show that 650℃ belongs to the aging temperature of the alloy. The beta transition structure obtained by hot working precipitates tiny alpha phase, with strength and elastic modulus increased. In the range of 700°C-850°C, the alloy can obtain the good comprehensive performance, and meet the requirement of related standards. The elastic modulus of the alloy is 94-100Gpa. With the increase of temperature in 950℃-1030℃, due to the precipitation of secondary acicular alpha phase or the generation of the cubic martensite phase, the strength is rised, along with the plastic declined. At the two temperature points of 650℃ and 850℃, the XRD spectras of Ti-6Al-7Nb alloy are diffraction peaks of alpha phase without that of beta phase. After the heat treatment of 1030℃, the cubic martensite phase has strong (002) and (101) diffraction peaks, and the energy of other lattice orientations is very weak. The elastic modulus of the alloy reaches a maximum of 108 GPa. Through metallographic observation, the start temperature of α+β→β transformation is in 900℃-920℃, and the end temperature of that is in 1010℃-1030℃.