A new style of flexible focus variable mirror which is forced by piezoelectric ceramic is designed in this paper. Finite elements method is used to calculate the mirrors deflection and the deviation of surface shape is quoted to evaluate the mirrors imaging quality. When the maximum deflection is 9μ m, the radius of mirrors curvature is varying from 610mm to 590mm and the PV val ue of deviation is 1μm, the relative deviation of surface shape is 0.3%．