Abstract: To address the issue of excessive porosity in laser powder bed fusion (LPBF) fabricated AlSi10Mg alloy during fusion welding, the welding formability of the LPBF fabricated AlSi10Mg alloy using the alternating current tungsten inert gas (TIG) welding process was investigated based on the Taguchi method, and the microstructure and properties of the joints were analyzed. The results indicate that alternating current frequency is the most significant factor influencing porosity, while welding current is the most significant factor influencing penetration depth. Microstructural analysis indicates that the weld microstructure is primarily composed of a gray α-Al matrix phase and bright white eutectic Si phases distributed at grain boundaries. A high density of small-sized pores exists in the central region of the weld, whereas larger pores appear at the top and bottom of the weld. A micro primary pore band distributed along the fusion line is formed near the fusion line. The root cause of pore generation is the hydrogen in the base metal. The optimal combination of welding process parameters is a welding current of 160 A, a welding speed of 110 mm/min, a wire feed speed of 16 mm/s, and an alternating current frequency of 110 Hz. Under these parameters, the transverse porosity of the weld reaches a minimum value of 3.20%; the longitudinal porosity is 2.13%; the penetration depth is 1.72 mm. The average microhardness and tensile strength of the joint are 76.56 HV_0.2 and 174.79 MPa, respectively.