Online detection and grouping of the tapered roller grinding ball surface need to achieve higher accuracy and faster speed. According to its technical requirements and characteristics, three coordinates measuring principle was adopted to improve the accuracy of measurement. The multiple triggering of probe was used to measure the same workpiece at the same time to realize the measurement speedup. According to the coordinates of all probe head fitting the spherical ball surface, and then by measuring software to calculate the radius of curvature of ball surface and relative to the outer circular pulses, at the same time grouping according to calculated data, the basis was provided for the assembly process of the bearing. The final assembly accuracy and speed of bearings are improved.