The invention discloses an automatic wire-feeding friction stir welding method for butt joint of dissimilar metal materials. The automatic wire-feeding friction stir welding method comprises the following steps that 1, welding pieces are in butt joint with each other and are clamped, an interval is formed between the welding pieces, strip-shaped welding wires are led out from a wire-feeding gun, a straightening wheel set, a pre-buried wheel and a leveling wheel are sequentially placed on the interval, the strip-shaped welding wires are straightened through the straightening wheel set, then obliquely downwards fed into the interval through the pre-buried wheel and later leveled through the leveling wheel, and the ends of the strip-shaped welding wires are arranged under a stirring head; 2, a welding machine is started, the stirring head starts vertical downwards feeding, later a stirring needle is pressed into the interval where the strip-shaped welding wires are stored, welding is started, and in the welding process, the wire-feeding speed keeps consistent with the welding speed; and 3, the stirring head is lifted, then wire feeding is stopped, and the strip-shaped welding wires are cut off. According to the automatic wire-feeding friction stir welding method for butt joint of the dissimilar metal materials, generation of chemical compounds between metal can be reduced, the interface temperature is decreased, the residual stress is reduced, a welding joint is prevented from generating holes, and the mechanical property and the welding efficiency of welding connectors are improved.