The protrusion of angular contact ball bearings is the distance of the same end face of the inner and outer rings under the axial preload, which is the basis for pairing precision angular contact ball bearing. To realize the rapid and precise measurement of the protrusion, an optical precision measurement method is proposed and a measuring device is developed. By replacing the bearing positioning claws of different sizes, the protrusion amount of the 7208C, 7208AC, 7308B, and 7408B bearings can be measured. The Hertz contact between bearing ring and roller is analyzed, and the relationship between bearing protrusion and axial load is revealed. The change trend of the bearing protrusion slows down as the axial load increases, and gradually tends to linear correlation. Based on the finite element method, the deformation analysis and simple harmonic vibration analysis of the frame and inner ring drive of the measuring device are carried out. The vibration amplitude of the sensor probe is reduced to 0. 029 μm after optimization. The 7008C (P2) angular contact ball bearings protrusion is measured. The verification results show that the measurement accuracy reaches 0. 5 μm, and the measurement deviation of the sample is less than 0. 2 μm.