Simulation research has revealed the atomic mechanisms of sintering in high-entropy alloys. Using computational fluid dynamics and molecular dynamics simulations, researchers systematically investigated the sintering behavior of AlCrFeCoNi high-entropy alloy nanoparticles in additive manufacturing under different temperatures, particle sizes, and grain boundary conditions. The simulations show that sintering proceeds through two stages: initial particle contact and stable growth of the sintering neck, with surface and grain boundary atomic migration dominating the entire process; increasing temperature significantly accelerates the neck growth rate. Grain boundaries can effectively alter atomic migration paths, while particle morphology and microparticle doping jointly determine the degree of sintering, and surface segregation of Al plays a prominent regulatory role in the overall sintering process. This work provides an atomic-scale theoretical basis for parameter optimization in additive manufacturing of high-entropy alloys, and is worthy of attention from readers in the materials and additive manufacturing fields.