In this paper,we derive a nonlinearequation of corneal asphericity (Q) usingthe tangential radius of curvature (rt) on every semi-meridian. We transform the nonlinear equation into the linear equation and then obtain theQ-value of cor-neal semi-meridianby the linear regression method.We find the 360 semi-meridional variation rule of theQ-value us-ing polynomial function. Furthermore, we construct a new 3D corneal model and present a more realistic model of shape of the anterior corneal surface.