Abstract: To investigate the influence of the laser welding process on the microstructure evolution and mechanical properties of duplex stainless steel joints, low-nickel duplex stainless steel S32001 was taken as the research object, automatic laser welding was conducted, and the relationship between the microstructure and mechanical properties was studied. The results indicate that under different welding process parameters, the weld surface is well formed, the microstructure is composed of austenite and ferrite, and secondary austenite is precipitated in the weld metal zone and the heat-affected zone. The microhardness of the joint exhibits a “W-shaped” distribution, with the highest hardness in the weld metal zone, the lowest hardness in the heat-affected zone, and intermediate hardness in the base metal. When the heat input is 12 J/mm, the hardness of the joint reaches a maximum of 322.7 HV ± 9.3 HV. When the heat input is 21 J/mm, the tensile strength and elongation after fracture of the joint reach maximum values of 904.9 MPa and 52.70%, respectively. The morphology of the tensile fracture is composed of cleavage planes, voids, and dimples. Some micron-sized inclusions can be observed, and the fracture mode of the weld is quasi-cleavage fracture.