Aspheric mirrors are often tested by interferometer with two different ways ensuring the correctness of the testing result. As the two most common methods, null correctors and CGHs are often used in actual testing at the same time. Considering the accuracy of CGH is higher than null lens, it can be also used to calibrate the accuracy of null lens. However, the central section of null correctors can’t be tested by traditional CGHs. In the article, tilted CGHs are proposed to test null correctors. In addition, we provided an experimental demonstration by testing a null corrector with tilted CGH applying the maximum likelihood (ML) algorithm. The result demonstrates the feasibility of the testing of null correctors by tilted CGHs with ML algorithm.