GH3536 nickel-based superalloy was fabricated by selective laser melting technology (SLM) and heat treated at 900 ℃ for different holding times (0.5 h, 1.0 h, 1.5 h, 2.0 h, 2.5 h). Optical microscopy, X-ray diffraction, electron backscatter diffraction, nanoindentation and Vickers hardness were used to analyze the microstructure and mechanical properties of the deposition and different heat treatment states. The results show that there are fine dendrites in the deposited microstructure, some of them disappear after heat treatment, while some of them change into recrystallized grains. Grains of horizontal plane (Z plane) in the deposited state mainly grow along the (111) plane and (001) plane. After heat treatment, the grains mainly grow along the (101) plane. The hardness of the deposited sample is 303 HV_0.5, and Young's modulus is 218 GPa. After heat treatment, Young's modulus is basically unchanged, but the hardness significantly decreases to about 273 HV_0.5.