Ni-based single crystal superalloys have been widely used to produce turbine blades for advanced aero-engines because of the super temperature-related microstructural stability and comprehensive mechanical properties. However, due to effects of the high temperature and complicated stresses in service, the microstructures of superalloys might gradually evolve and fail in different modes. The present paper reviews the progress of microstructural stability and mechanical behavior including the γ’ phase rafting, TCP phase precipitation, high temperature creep, low cycle fatigue and thermomechanical fatigue of single crystal superalloys. The addition of Ru improves the creep life of superalloys, but also indirectly promotes the occurrence of “topological inversion”. On the other hand, with the increase of aging temperature and time, the contents of refractory elements in m phase rise significantly. With the increase of applied tension stress, more m phase precipitate from the γ matrix, whereas inverse tendency is shown under compression stress. Numerous planar defects are formed during precipitation of m phase, and these defects promote the nucleation of P and R phases. During high temperature and low stress creep, an important dislocation a<010> superdislocation is observed, which moves in the γ’ phase slowly by a combination of slide and climb. Under very high temperature, incubation with accelerating creep rate occurs before the primary stage, which relates to the extending process of the γ width. At last, the stacking fault energy is significantly reduced after Ru additions, and thus a series of complex deformation mechanisms occur during low cycle fatigue, e.g. stacking faults penetrating γ/γ’ interface, trailing a/6<112> Shockley dislocations shearing into the γ’ phase. During thermomechanical fatigue, the life of superalloys is influenced by the site of crack initiation, microstructural evolution and oxidation resistance.