Fiber laser-tungsten inert gas (TIG) hybrid welding is applied to TC4 sheet with the thickness of 1 mm. The influences of welding parameters such as laser power, arc current, the distance of heat sources and the shielding gas on weld bead formation are studied. The metallographic structure and mechanical properties are also analyzed. The results indicates that with the increasing of arc current and the ratio of He in main shielding gas, the welding fusion area gradually increases. With the increasing of laser power and the distance of heat sources, the welding fusion area changes in fluctuation. The tendency of undercut is related to the heat input of hybrid heat sources. With the rising of concentration and input of the energy, the undercut depth on the back side of the welding seam decreases. The efficiency of shielding is mainly determined by the heat input of arc. The more input heat is, the poorer protective effect is. The tensile strength of hybrid welding joint under optimum welding conditions is larger than the base metal, and the elongation is smaller than the base metal. This is related to the distribution of martensite in the welding seam. The fracture takes place in the base metal.