The aspherical mirror surface quality testing by using compensation null lens in interferometer is described in this paper. For 310mm, f/0.5 hyperboloid mirror microcrystalline components, based on the theory of aberration compensation, a kind of null lens system which is composed of three pieces of spherical lens is developed. A certain amount of spherical aberration is introduced to the null lens for compensating the deviation of aspheric surface in a normal direction. The design result shows that the primary aberration and the senior aberration are balanced well, the MTF is closed to the diffraction limit and the residual wave aberration (RMS) is less than 0.004λ (λ=0.6328μm). Every indicators of the system meets the requirements of high precision detection of null lens system design. In this paper, the errors caused by the manufacturing, testing and assembling of the null lens system are analyzed. Those errors can be divided into the symmetric error and the asymmetric error. Using the correction method, the influence of the asymmetric error is minimized which seemed bigger than the asymmetric one. Finally, analysis results show that the total residual wave aberration of the system is less than 0.0072λ, which satisfies the requirement of aspheric testing. This null lens system has been applied to aspheric processing.