Residual stress is an inevitable factor in microelectromechanical system (MEMS) surface micromachining,it affects the performances of the devices. In this paper,the formulas for calculating the pull-in voltage and the stroke of an electrostatic micromirror with residual stress existed have been derived by introducing an equivalent mechanical model,and the effect of the residual stress on the eigen-frequency of the micromirror is analyzed. The result shows that the eigen-frequency increases with the residual stress. The micromirror surface profile,under different residual stress,is tested by a white light interferometer. Experimental results indicate that the residual stress makes a warp on the surface,and it declines Strehl ratio and lower the image quality.