Based on Gleeble isothermal hot compression test, combined with OM, SEM and EBSD analysis methods, the flow characteristics and microstructure evolution of a new hot extruded third generation nickel-base powder superalloy FGH4113A (WZ-A3) during superplastic compression deformation was systematically studied. The superplastic deformation behavior and deformation mechanism at different temperatures of 1050 and 1100 ℃, different strain rates of 0.001 and 0.005 s_^-1, and different amount of deformation (strain) were presented. The results shown that FGH4113A (WZ-A3) alloy exhibited good superplasticity during hot compression deformation, and no cavities or cracks were observed. The grain size tends to grow at 1100 ℃/0.001 s_^-1 after large deformation (60%-80% deformation), while grain size has little change under other deformation conditions. In the process of superplastic compression deformation, the accumulated dislocation is annihilated mainly by dynamic recovery and dynamic recrystallization, and grain boundary slip is the main reason for large deformation without cracking. The results lay a good foundation for the development of superplastic isothermal forging process of FGH4113A (WZ-A3) alloy.