The invention belongs to the technical field of metal additive manufacturing, and provides an aluminum alloy laser-TIG composite additive manufacturing method. According to the composite additive manufacturing method, a laser and an electric arc are used as composite heat sources, and a TIG mode is adopted, so that additive manufacturing forming of the aluminum alloy thin-wall type (single-channelmulti-layer) structure is realized. The method comprises the following steps of S1, determining the relative position relation among the laser, the electric arc and a wire, and carrying out base plate preheating treatment; S2, forming aluminum alloy laser-TIG composite additive single-channel single-layer structure; and S3-S5, forming aluminum alloy laser-TIG composite additive thin-wall type (single-channel multi-layer) structure. According to the composite additive manufacturing method, the defects that formation is not easy when the laser is used as a single heat source due to the fact that the reflectivity of the aluminum alloy is high, and deformation is serious and the forming quality is poor when the electric arc is used as a single heat source due to the fact that the heat input quantity is high are overcome; and the method is suitable for additive manufacturing of aluminum alloy thin-wall type (single-channel multi-layer) structure and can effectively inhibit air hole defects.