In order to solve the problem of astigmatism which affects the clarity in virtual system, a type of reflection surface design is put forward for astigmatism correction in the full field, and the design algorithm of the anastigmatic reflection surface based on differential equations is presented. The designed anastigmatic surface can correct astigmatism at each field of view effectively and decrease the size of dispersion spot. An astigmatic surface is applied in the off-axis virtual display system with the field of view of 60°×40°, and the radius of dispersion spot at each field of view is less than that of the Airy disk. The design results of the anastigmatic reflection surface are compared with the results designed by a spherical and a toroidal surface with the same parameters. It is found that the root mean square radius of dispersion spot and the absolute value of astigmatism designed by anastigmatic reflection surface are less than 20% of the result designed by a spherical reflective surface at the full field, and they are less than 20% of the result designed by a toroidal reflective surface at the margin field.