Spray forming (SF) is a novel rapid solidification technique. Compared with traditional cast & wrought and powder metallurgy technique, it has the advantages of less segregation and shorter process. In this work, a new third generation powder metallurgy (PM) superalloy FGH100L was prepared by SF+hot isostatic pressing (HIP)+isothermal forging (IF)+heat treatment (HT) process. The effects of solution heat treatment temperatures and preparation process on the microstructure and mechanical properties of FGH100L alloy were studied. The results show that the microstructure of SF+HIP+IF state FGH100L alloy is very sensitive to changes of solution temperature. With the increase of the solution temperature (1110~1170 ℃), the grain size of the alloy grew, and the size of the γ' strengthened phase first increased and then decreased. Its hardness, tensile strength and plasticity at room temperature/high temperature all show a trend of increasing followed by decreasing. The quantitative equilibrium of three sizes of γ' phase in the alloy is more reasonable, the microstructure of the alloy is the best, and the hardness and room temperature/high temperature tensile properties of alloy have the highest parameter values at 1130 ℃. At the same temperature, the grain size of FGH100L alloy increased first and then decreased under different processing conditions of SF, SF+HIP+HT and SF+HIP+IF+HT. The morphology of grains changed from subspherical to polygonal to subspherical. Alloy grain size increases, and the grain boundary bending degree decreases in the process of SF+HIP+HT. Due to SF+HIP+IF+HT process, the alloy recrystallizes, refines the grain, and presents chain-like structure, forming curved grain boundary and having higher yield strength. Under SF+HIP+HT and SF+HIP+IF+HT processes, the tensile fracture of the alloy at room temperature changed from intergranular brittle fracture to transgranular and intergranular mixed fracture, and the tensile fracture at high temperature was intergranular fracture.