Owing to the high melting point of tungsten (W), achieving high-density W and W alloy components is challenging. In this study, different methods were used to study the effects of process parameter adjustment and Re addition conditions on the density, microstructure, and mechanical properties of W-Re alloys. Results show that the density of the W-Re alloy is directly proportional to the laser power and inversely proportional to the scanning speed. When the laser power was 180 W, the scanning speed, scanning interval, and maximum density are 600 mm/s, 0.03 mm, and 96.1%, respectively. The process parameters were optimized to reduce pore formation and achieve fine-grain strength, realizing the maximum hardness of 550 HV. The displacement solution of Re induces a right shift of the diffraction peak of W. At high temperatures, Re can strengthen the solution of W. The density, hardness, crack size, and morphology of the selective laser melted W-Re alloy are better than those of the pure W alloy.