_{: Twin boundary as a low energy stable interface and easy to be regulated in low stacking energy metals has become a hot focus in recent years. There are a lot of annealing twin structures in the solid solution GH3625 alloy. In this paper, the annealing twin structure evolution and the fracture behavior of GH3625 were studied by in situ tension at room temperature, which combined with Scanning Electron Microscopy (SEM) observation and Energy Dispersive Spectrometer (EDS) analysis. The results show that the deformation mode in the twin structure of GH3625 alloy is mainly single slip in the process of tensile deformation, and the twin boundary gradually bends with the increase of deformation during the process of tensile and fracture, but the twin boundaries always exists in the alloy structure, which hinders the dislocation and has good mechanical stability at room temperature. There are both ductile fracture and brittle fracture in GH3625 alloy, the carbide segregation is the main cause of grain boundary crack and intragranular holes formation.}