To solve the problem of poor roughnesses for heavy curved freeform surfaces in prism processing, a Head Mount Display (HMD) prism with decentered aspheric surfaces was developed. All the optical surfaces of the prism were rotationally symmetrical aspherics, which showed a better processing property as compared with freeform surfaces. A short focal length and a large field of view were obtained by controlling the surface curvatures and tilt angles, and the aberration was corrected by optimizing aspheric coefficients. Experiments show that the HMD prism has an exit pupil of 6 mm and a field of view of 55°. At the frequency of 30 lp/mm, the axial Modulation Transfer Function(MTF) is over 0.2, the off-axial MTF is over 0.1, and the maximum distortion is -5.37%. The test and experiment on the prism demonstrate that the surface roughness has been greatly improved to a lower level for the aspheric surfaces, which avoids the image blurring and improves the performance of visualization.