Based on the elasticity theory of thin plates, the basic analysis on annular line load model and deflection equations based on this model was given. Aiming to generate a large saggitus variation using a smaller force, mathematical analysis on different mirror thickness and actuate ring radius was done by using MATLAB, the corresponding optimal value is 2~4 mm and 1/2 mirror's clear radius. One QeB variable curvature mirror prototype, whose diameter and thickness is 100 mm and 3 mm respectively was designed, fabricated and the whole structure's first ten vibration mode analysis was given. The surface accuracy of the assembled prototype is nearly λ/30. Finally, the capability in altering curvature and maintaining surface figure accuracy was tested experimentally. By improving the variable curvature mirror structure, the QeB variable curvature mirror could provide a saggitus more than 30 wavelengths(632.8 nm) and the degradation of surface figure accuracy is weakly correlated to the variation of radius of curvature.