Abstract: Based on molding principle of selective laser melting (SLM), the heat source model was simulated by body heat generation method, and the load of moving laser heat source was realized by ANSYS parametric design language (APDL); then the single-layer transient temperature field and molten pool morphology of Hastelloy-X superalloy during SLM process were simulated by finite element model. The simulation results were verified by tests. The high temperature creep property of SLM molding specimens was investigated and compared with Hastelloy-X superalloy hot-rolled rods treated by solution. The results show that the body heat generation method could simulate the single-layer transient temperature field during SLM molding well, and the calculated molten pool size and primary dendrite spacing agreed well with the experimental results. Under the same creep test condition, the steady-state creep rate of SLM molding specimen was much lower than that of Hastelloy-X superalloy hot-rolled rods treated by solution; however, the creep stress index of them were similar, and creep deformation were both dominated by movement and climbing of dislocations.