To investigate the effects of alloying Ta and Mo elements on the strength and morphology of the γ′ phase of Co-Al-W-based high-temperature alloys, the γ′-L12 supercell structure was constructed, doping calculations were performed at six nonequivalent sites, and the energy structure and mechanical properties were analyzed; and Co-8.8Al-9.8W-2X (X = Ta, Mo) alloys were prepared, and the alloys were deformed in 5% and 10% compression. The γ′ phase morphology and dislocation morphology of the alloy were analyzed using transmission electron microscopy (TEM) technique. The results show that the Ta atoms preferentially occupy the Al2 position and the Mo atoms preferentially occupy the W6 position during alloying, and the Ta atoms occupy the Al2 position, which increases the strength and tissue stability of the γ′-L12 doped structure, while the Mo atoms doping at the W6 position has the opposite effect. The γ′ phase shape can be maintained as cubic when the alloy is compressively deformed, and the dislocation damage to the γ′ phase is more limited, while the strength of the γ′ phase of the 2Mo alloy is reduced due to the preferential occupation of the Mo atoms in the W6 position, and the γ′ phase shape is changed from cubic to raft when the alloy is compressively deformed, and the dislocation damage to the γ′ phase is more serious.