In this research, the microstructure evolution of an as-cast 3rd generation Ni-based SX superalloy during hot deformation was investigated using Gleeble1500 hot simulator, and the dynamic recovery and dynamic recrystallization (DRX) processes in the interdendritic zone and the vicinity of residual eutectic were studied using SEM/EBSD and TEM, to clarify the possibility of DRX during hot deformation. Firstly, dynamic recovery mainly involves the interaction of dislocations with the γ' phase. Dislocations on different slip planes were hindered by the γ' phase, thus accumulated at the γ/γ' interface and reacted to form regular dislocation networks. Then, the dislocation density of the network was increased gradually by moving dislocations generated in the γ matrix. Meanwhile, dislocation networks may also interact with each other by dislocation slip & climb, forming LAGBs with greater misorientation or even HAGBs. Finally, high density of dislocations accumulated near the residual eutectic leads to a sufficiently large misorientation gradient, promoting the nucleation of DRX. Overall, controlling plastic strain by optimizing component design remains the most important means of suppressing recrystallization. Optimizing the content of refractory elements to suppress dendrite segregation and eliminate eutectic is also a potential way to avoid recrystallization. This study will provide useful guidance for understanding and controlling the recrystallization of Ni-based SX superalloy components during fabrication.