In order to provide theoretical guidance for production process contorl and performance optimization, the microstructure evolution and heat treatment process in the production procecss of GH5188 cobalt-base superalloy were investigated by SEM, EDS and Thermo-Calc software. The result indicates that the main phases of GH5188 alloy include γ, M6C and M23C6. The 1200°C/20h could reduce segregation of as-cast microstructure. Hot-rolled microstructure have a fine grain size, and a large number of aligned carbides precipitate along rolling direction. In the cold-rolled microstructure with serious grain deformation, granular M6C was found to be predominant phase. when the annealing temperature is higher than 1170°C, secondary carbides at the grain boundaries dissolved back into γ and recrystallized grain can grow in normal way.