The technology and joint properties of TC1 titanium alloy using CO 2 laser welding were investigated. The problem of melting pool protection was resolved by designing a rear-cover and a special clamp. Joints with good quality were obtained, which had no pore, crack and surface-oxidation. In addition, the welding speed could reach 3m/min with the plate of 1.5mm thickness being penetrated. The profile of joint cross sections was "sandglass". Through analyses of the microstructure and mechanical property, it has bee found that the weld with the relatively coarse microstructure still has good performances.