By means of heat treatment at different regimes, microstructure observation and XRD analysis, an investigation has been made into the influence of heat treatment on the phases constitution and distribution regularity of GH4169G alloy. The results show that under the experimental conditions, microstructure of GH4169G alloy consists of γ matrix, particle-like γ′,disc-like γ^〞and δ phases, and the coherent interfaces are kept between the phases. Thereinto, microstructure of directional aging treatment ITF-DA-GH4169G alloy consists of a few γ′phase, lots of γ^〞 and γ phases, however, long-time aging treatment ITF-DA-LTA-GH4169G consists of a few γ′,lots of γ^〞, γ and needle-like δ phases. As the Nb atom diffuses into the lattice of γ′  phase during the aging treatment,γ^′ -Ni₃Al phase with L1₂ structure is transformed intoγ^〞-Ni₃Nb phase with DO₂₂ structure when the Nb and Ni atoms on (001) plane of γ′ phase migrate along 1/2<110> direction. With the growth of γ^〞 phase during the long term aging, the given crystal plane in the new parallelepiped migrates along the 1/6<112> direction, which makes the γ^〞 phase transform into δ-Ni₃Nb phase with DO_a structure. Moreover, the γ^〞 phase may grow up into the disc-like configuration along the c-axis direction due to the restriction of the a- and b-axis coherent interfaces. And it is a main reason that the δ-Ni₃Nb phase grows into needle-like configuration along the (100) plane due to the {200}_δ plane ofδ phase keeps coherent interface with {111}_γ plane of γ matrix phase.