Abstract: On account that the mall prism has the biggest facial contour deformation tolerance corresponding the smallest deviation angle at different incident height of lens,basic principal for symmetrical refraction design of arched Fresnel concentrator lens is presented,and the(transmittance) and convergent property of transmitted light for symmetrical design and conventional design are compared.The facial contour deformation tolerance of Fresnel lens can generally arrive at 15～20 degree by this design method,and it's optical efficiency is higher than that of conventional designed Fresnel lens,Although there is off-focus phenomenon for the Fresnel lens designed by symmetrical refraction,transmitted light can still be focused on the sloar cells if the parameters are selected properly.