On the basis of the asymmetric distortion from asphere measurement by a Computer-generated Hologram(CGH), three basic distortion models were analyzed, and an effective correction method for asymmetric distortion was proposed. By using a few fitted parameters, the method can correct the asymmetric distortion accurately, reduce data point pairs needed by distortion correction and can avoid over-fitting effect. Furthermore, the distortion of whole interferometric system was simulated, and its distortion was corrected by the proposed method. The simulating result shows that the relative residual of the correction is less than 0.2%. Finally, an off-axis CGH was designed and fabricated to verify the reliability of the correcting method and an asphere surface was tested with this CGH. Then, the correcting method mentioned above was used to correct the testing result, and the correcting result was taken to fabricate the asphere iteratively. The experiments show that the aspheric surface figure converges at 1.8 nm RMS (Root Mean Square) eventually. These results verify the reliability of the correction method.