It is presented that a SiC unrotational-symmetric aspherical optics whose surface equation is z=3λ(x³+y³) (where x, y is normalized coordinate, λ=0.632 8 μm, Φ150 mm) has been manufactured. Both digital-controlled polishing and hand working are used to modify the surface figure. The tilt component is subtracted to minimize the material removal without any effect on the surface figure in the polishing process. The material removal of the lowest point on the surface is 3.8 μm before subtracting tilt, while the removal is 2.06 μm after subtracting tilt. A non-null testing method based on digital mask is proposed to test this surface. The Zygo interferometer with flat reference wavefront is applied. The testing result can be divided into three parts: the derivation between the actual surface figure and the ideal one, the derivation between ideal surface figure and the reference wavefront, and the non-null error. The second part can be calculated ahead and made the system error of testing process with the transforming tool of Metropro. Thus, it can be eliminated automatically in the testing process. The third part is proven to have little effect on testing result by an experiment of testing a known sphere model, so it can be ignored. Thereby, the surface figure error (the first part) can be obtained within single measure. The final surface figure is 0.327λ (PV) and 0.025λ (RMS) by means of the non-null testing method, which achieves the prospective goal.