Fe18Ni23Co25Cr21Mo8WNb3C2 superalloy powders were synthesized via atomization method, and phase composition, morphology and thermal stability of composite powders were respectively characterized. Based on the above analysis, atomized alloy powders were fabricated by vacuum hot-pressed sintering and further second sintering. The sintering Fe-Ni-Co-based superalloy mainly consists of austenite phase and M6C carbide phase, which was a strengthening phase. Experiment results indicate that superalloy have uniform structure, high tensile strength and low elongation after vacuum hot-pressed sintering. Further second sintering, microstructure of superalloy become more homogeneous, the tensile strength decreases slightly and the elongation rate significantly increases.