The size, the distribution and the shape of secondary γ′ in powder metallurgy superalloy FGH95 were researched by field emission scanning electron microscopy, the alloy was long-term aged at 750 °C for 5000 h, in order to provide a theoretical basis for its application in newly aero-engines. The results show that with prolonging of the aging time, the morphological character of secondary γ' is unstable, and its size does not follow the law of LSW theory. During 0~500 h the splitting of reverse coarsening occurs in the second γ', resulting in splitting of a single butterfly precipitate into a group of eight cuboids. In 500~1000 h, the split γ′ coarsens to a certain extent and then start to split again after 1000 h. With prolonging of the aging time, they gradually grow after 2000 h, ellipsoidal secondary γ' phase become more and more. It is proved that the shape evolution strongly depends on the elastic interaction between γ' precipitates. Shape changes in order to minimize the sum of interfacial and elastic interaction energies.