Previously only lens with aspheric surface for correcting spherical aberration was analyzed. Based on the third-order aberration theory,a method is put forward to gain inifial data of the aplanatic lens(including singlet and doublet)with aspheric surface. Its validity is validated by the optical design software Zemax. Several curves are given based on lots of calculations. Curve of the relative aperture and spherical aberration is analyzed. All these analyses are beneficial to optical design.