Based on Erfle lens structure, a traditional refractive eyepiece which can be used in the helmet display system is designed. On this basis, the diffraction surface is added, and the refractive and diffractive eyepiece is optimized. The basic structural parameters of the two systems are the same. The exit pupil distance is 27 mm and the diameter of the exit pupil is 8 mm. Compared with the traditional refractive structure, the total length of the refractive and diffractive eyepiece is reduced by 11%, the weight is reduced by 23%, and the distortion is reduced by 59.45%. Considering the influence of bandwidth integral average diffraction efficiency of diffractive optical elements on the system′s modulation transfer function(MTF), the MTF of the field-of-view on the axis and the minimum MTF of the refractive and diffractive helmet eyepiece are higher than 0.68 and 0.28 respectively at the spatial frequency of 40 lp/mm, which can meet the design requirements. It can be used in the virtual reality helmet display system.