Q-type asphere has broad application prospect which has been applied in optical system design increasingly. But there is no easy or high-efficiency way to test the Q-type aspherical surface precisely until now. Aimed at the testing of Q-type asphere in the process of ultra-precision turning, a method based on MATLAB and Taylor Horbson PGI-1240 aspheric profilometer is proposed. First, we have fabricated a single crystal cupreous Q-type asphere whose aperture is 11.8 mm by Nanoform 700 single point diamond ultra turning lathe. And the testing result shows that, the PV and RMS values of Q-type asphere surface shape error are 0.1963 μm and 0.03412 μm. It meets the requirement that PV value should be less than 0.2 μm as well as RMS value should be less than 0.04 μm. This testing method can get precise surface shape error and provide data support for next stage of turning.