A surface measurement method of convex aspherical lens with large clear aperture is proposed based on an aspherical compensation mirror. It overcomes the difficulty that multiple lenses are needed for compensating the normal aberration of convex aspherical lens. In addition, it simplifies the design and reduces the cost. Aspherical lens measurement system with large diameter is designed and implemented. Source of error is systematically analyzed, and elimination method of error is also proposed. In order to verify the feasibility of the proposed method, a convex aspherical lens with an aperture of 270 mm is inspected. The peak valley (PV) value and root mean square (RMS) of the tested aspherical surface are 0.585λ and 0.083λ, respectively. This method provides a technical reference for large aperture aspherical surface testing, and also can be used in the field of rough polishing testing.