In order to eliminate the mixed grain structure of forged Ni-based superalloy parts, the heat treatment process of δ phase aging + recrystallization annealing was proposed. During aging, the δ phase can precipitate directly or indirectly by the transformation of γ″ phase. The alloy with precipitated δ phases were both annealed at high temperature and then immediately cooled by water. It was found that the aging routes and aging times greatly affect the microstructure evolution during recrystallization annealing. In the aging process, the directly-precipitated δ phase mainly distributes at grain boundaries. With the increase of aging time, some δ phases precipitate inside grains, and the main morphology is short-rod like. The distribution characteristic of the indirectly-precipitated δ phase is mainly intragranular needle like and intergranular short-rod like. The short-rod δ phase has weak interaction with dislocations during annealing and is mainly responsible for pinning grain boundaries, while the long needle-like δ phase can promote the formation of sub-grains. That is why the indirect aging is favorable for the recrystallization nucleation, and can also effectively hinder the growth of grains to avoid abnormal growth of recrystallized grains.