The deformation and damage behavior of the single crystal Ni-based alloy during elevated temperature creep were investigated through analyzing creep properties and microstructure. The results show that the creep life of Ni alloy under the condition of 1040 °C/137 MPa is 556 h, displaying an excellent creep resistance of Ni alloy. The creep feature of Ni alloy at steady state is the dislocation glide in γ phase and dislocation climb over the γ′ rafts. In the late stage of creep, the deformation feature of Ni alloy is that the γ′ rafts are sheared by the dislocations of cross-slip, which forms the Kear-Wilsdorf (K-W) locks to restrain the dislocation glide and cross-slip dislocation. The cross-slip dislocations cause the distortion of γ/γ′ rafts, thereby promoting the initiation of cracks along the γ′/γ interfaces and the interface fracture, which is the damage and fracture features of Ni alloy. The condition of σ>η/α is considered as the prerequisite for unstable crack propagation.