To realize the rapid, high-precision, and universal testing of concave aspheric surface, a non-null interferometry method is proposed in this paper, which takes the asphere as a spherical surface and measures it directly with an interferometer. Combined with the corresponding data processing methods, the test results of the aspheric surface are obtained. Firstly, the detection theory of this method is introduced, the calculation and removal models of retrace error and adjustment error are established, and the data processing method of shape error is studied. Secondly, taking two concave aspherical surfaces with different parameters as an example, the retrace error and adjustment error are simulated, which verified the effectiveness of the method. Finally, a non-null interferometry experimental setup of concave aspheric surface is performed, and its shape error is successfully obtained. By comparing the results with autocollimation method or LUPHOScan method, it is shown that the surface distribution and evaluation indicators of the results are highly consistent, which verifies the correctness of this method. This method provides an effective measurement method for concave aspheric surface with high precision, universality, and convenience.