Interfaces in a modified Inconel 718 containing compact precipitates were investigated using high resolution transmission electron microscopy. Morphology configuration and crystallography of the compact precipitate were confirmed as cube-shaped γ′ precipitate and all six faces were coated with a thin shell, these shells could be classified as three variants of disc-shaped γ″ precipitates on {001} planes of the matrix, and the [001] orientations (c-axis) of the three variants of γ″ precipitate shells were parallel to [001], [010] and [100] orientations of the matrix. The interfaces of γ″ precipitate/matrix, γ′ precipitate/matrix, and γ″ precipitate/γ′ precipitate were fully cube–cube coherent, and the atoms at both sides of the interfaces maintained a perfect match with no disordered structure transition region. It was suggested that the higher thermal stability of the modified Inconel 718 alloy than that of conventional Inconel 718 alloy was due to the morphology configuration of the compact precipitate and fully coherent interfaces among the γ′ precipitate, γ″ precipitate and matrix.