Abstract: SLM is one of the key technologies for rapid manufacturing of high-performance high-entropy alloy components. However, in the SLM process, the multi-parameter manufacturing space directly affects the microstructure of the material, thereby influencing the performance of high-entropy alloys. This study explores the comprehensive relationship among the multi-parameter manufacturing space, density, microstructure, and microhardness of SLM-manufactured Al_0.5CoCrFeNi bulk high-entropy alloy, providing theoretical references and a technical support for the SLM preparation of multi-parameter combination high-entropy alloys. The research results indicated that the optimal forming quality of the specimens was achieved with SLM process parameters of P = 100 W, v = 1500 mm/s, α = 67° and VED = 44.4 J/mm³, resulting in the lowest internal porosity, at 1.8%. Both lower and higher VED negatively impacted macroscopic forming quality. VED had a notable influence on phase distribution, grain morphology and average grain size. The SLM-manufactured Al_0.5CoCrFeNi bulk high-entropy alloy consisted of FCC and BCC phases, with the FCC phase content increasing from 99.73% to 99.98% as VED increased. The columnar grains became predominant, with the average grain size initially decreased and then increased. Low-angle grain boundaries exhibited an initial increase followed by a decrease, while high-angle grain boundaries showed the opposite trend. The microhardness first decreased and then increased to 244.3 HV, consistent with the variation trend of the average grain size with VED.