Abstract: The IC10 and GH4169 dissimilar superalloys were connected by electron beam welding, and the effects of different heat treatment processes on the microhardness and microstructure of IC10/GH4169 dissimilar superalloy welded joints were investigated by microhardness, optical microscopy and scanning electron microscopy. The results show that the weld seam is composed of columnar crystals and cellular structures, and there are two types of second phases, Laves phase and NbC, in the as welded weld seam. The aging treatment does not affect the macroscopic morphology of the joints, and there is no significant coarsening of the grains in the base metal areas on both sides. Under different aging processes, significant changes were observed in the microhardness of the GH4169 base material and weld zone, while no significant changes were observed in the microhardness of the IC10 base material.Under different aging processes, significant changes are observed in the microhardness of the GH4169 base metal and fusion zone, while no significant changes are observed in the IC10 base metal. The aging treatment results in a chain like distribution of precipitates at the grain boundaries of IC10 base metal zone, while the GH base material and weld zone shows the presence of γ′/γ″ and δ/η phases. The enrichment and segregation of elements during solidification makes the distribution of γ′/γ″ phase in the fusion zone uneven after aging treatment.