Abstract: In this paper,coating interface microstructure of TA7 titanium alloy,which was coated by the metal molybdenum with spraying in the argon atmosphere and then kept at high temperature diffusing,was analyzed with microscope,scan electrode microscope,electrode probe and X-ray diffraction etc.The results show that a solid,almost non-layer shape microstructure coating is available with subsonic speed plasma spray,the atom diffusing nearby interface would speed up metallurgical bonding,and affect titanium alloy microstructure nearby interface in certain degree.