Abstract: TC4 and TC17 titanium usually used on aeroengine blisk were studied.The microstructures were analyzed by metallograph and transmission electron microscope.The temperature during the welding process was also measured.The investigation showed that the joints included three zones, base metal(BM), thermal mechanical affected zone(TMAZ) and welding zone(W).The TMAZ microstructure was similar to base metal, alpha and beta phase were elongated along the stress direction, recrystallization occurred in the weld zone.The induced microstructures were different from the BM.The maximum temperature can reach 1 270℃ which exceeds the titanium beta transformation temperature.the tensile test result showed that joint tensile strength was equal to that of the TC4 at room temperature and 200℃, while the testing temperature is 400℃, the joint tensile strength can reach 95% of the TC4 base mental.