The creep behavior of a Ni base single crystal superalloy with [011] orientation under three conditions of temperature and stress level has been investigated. Creep deformation of the tested alloy occurs largely through dislocation activity in the γ matrix channel. Shearing of the γ´ precipitates is observed, while at higher temperature, this does not occur until late in life by means of the passage of superpartial dislocation.  At lower temperature (750 ℃) and high stress level, shearing of the  γ´ precipitates is observed in the relatively early creep through the passage of 1/3<112> dislocation, which leaves superlattice stacking faults (SSFs) in the precipitates. The creep behavior is closely related to microstructure evolution, the creep curve at 750 ℃ exhibits higher primary and steady creep rates, and thereby the creep life is shorter. Under the condition of 870 ℃ and 500 MPa, the steady-stage creep does not appear, it is suggested that the creep life is greatly influenced by the inhomogeneous slip band. At higher temperature and lower stress, such as 980 ℃ and 200 MPa, the alloy has longer creep life and lower steady creep rate. Observation of the dislocation configuration shows that the hexagonal dislocation network appears on the  γ/ γ´ interface at the early creep stage, the regular and denser dislocation networks can inhibit dislocation cutting into  γ´ phase and enhance the resistance of dislocation movement. In the later stage, $\gamma'$ precipitates are sheared by dislocation, which leads to an acceleration of creep rate.