In order to inspect the quality of the small-size parabolic mirrors, the focal length was measured by the parallel light focusing method, the eccentric angle was measured by rotating the measured mirror.The size of the dispersion spot was measured by combing with the image processing method, and a reduction measurement was proposed.Theoretical analysis and experimental verification of these measurement methods were carried out.The focal length, eccentric angle and size of the diffuse spot of the mirror under test were obtained. The results show that the relative error of the focal length is within 0.1%, the error of the eccentric angle is within 7%, the size of the dispersion spot is less than 0.2mm, and the measurement result is reliable. The design of this scheme provides a good idea for the detection of other small-caliber aspheric surfaces, and provides a good research method for reducing measurement errors and improving measurement accuracy.