Abstract: The Gleeble-1500 thermal simulation testing machine was used to simulate and study the grain evolution law of GH2787 alloy blade forgings under different heating temperatures and strain rates. The results show that the change of alloy grain size with heating temperature accords with the Sellars model of phenomenological theory; the strain rate and deformation temperature have significant influence on the uniformity of alloy structure, the sharp transition zone of deformation, improper matching of strain rate and forging temperature will all cause insufficient dynamic recrystallization of the alloy, and the unrecrystallized grains grow up sharply during heat treatment, forming single（or local） large grains, which will destroy the uniformity of grains.