By means of creep property test, microstructure observation and FEM analysis of the stress field near the voids, the influence of the microstructure defects on creep behavior and microstructure evolution of single crystal nickel-based superalloys was investigated. Results show that the plasticity and creep lifetime of the single crystal nickel-based superalloys are obviously decreased by microstructure defects. During high temperature creep, the stress isoline near the voids displays the feature of acetabuliform distribution, and possesses bigger values in the direction of 45° angle to the applied stress axis. That results in the g￠ phase transformed into the rafted structure in the direction of 45° angle to the applied stress axis, and the circular voids defects are elongated into the ellipse in the applied stress axis direction. During creep, smaller values of the stress distribution are in the up and down regions of the circular voids, and the maximum value of the stress distribution appears in the apices region at the sides of the void. Furthermore, the fact that the value of the stress distribution increases as creep goes on results in the germination there and expanding vertically to the stress axis of the cracks, which is a main reason of creep lifetime decrease of the alloys.