The angle of view of virtual reality head-mounted display is analyzed, optimizing the diameter of the lens and the distance of exit pupil. The spherical and non-spherical lens are designed and their disc of confusion and off-axis aberration is compared by using Zemax. The conclusion is that the non-spherical lens can improve the image significantly. Distortion resulted from the lens is corrected by the software. Non-spherical lens have little distortion and large viewing angle, which can satisfy our needs.