Selective laser melting was used to fabricate a GH3536 alloy. The effects of hot isostatic pressing (HIP) and solution treatment (ST) on the microstructure, mechanical properties, and fatigue crack growth properties of the GH3536 alloy were investigated. The results show that there are molten pool, columnar grains, dendrites, holes, and cracks in the as-deposited alloy. The HIP process can effectively heal defects, eliminate molten pools and dendrites, and make all grains grow into equiaxed grains. Besides, it can lead to the continuous precipitation of carbides along the grain boundary. After ST, many carbides dissolve back into the matrix. The tensile strength, hardness, and elongation of the as-deposited alloy are 782.1 MPa, 227.9 HV, and 17.7%, respectively, and defects are essential factors affecting the plasticity. After the HIP process, the strength and hardness of the alloy decrease to 693.7 MPa and 170.4 HV, and its elongation increases to 34.7%. After the ST process, the strength, hardness, and elongation of the alloy increase to 741.0 MPa, 180.6 HV, and 48.7%, respectively. In comparison, the fatigue crack growth resistance of the as-deposited alloy is less than that of the alloy after HIP and ST are improved.