To meet the need for rapid, high-precision measurement of the radius of curvature for large quantities of spherical optics, a radius measurement method based on differential confocal detection is proposed in this study. Firstly, scan a templet whose radius is known on its confocal position axially to obtain the fitted linear function; Secondly, replace the templet to the test sample in sequence, capture the differential confocal intensity without scan, map the single intensity to defocus with the linear function; Finally, calculate the radius under test by defocus and radius of template. Simulation and experiments show that the measurement accuracy is 12.2 ppm, and the measurement efficiency is 59 times higher than the traditional differential confocal scanning measurement. The measurement proposed only needs scanning once and replacing Sn N times to realize fast, high-precision, radius detection of N pieces of spherical surface. The proposed measurement provides a new way for high-efficiency and high-precision measurement of large quantities of spherical lenses.