The crossed roller bearing is a special type of bearing with split inner ring and rotating outer ring. In the crossed roller bearing, the cylindrical rollers are arranged vertically on the 90 degree V-groove rolling surface through the spacer keeper, so that the crossed roller bearing can withstand radial load, axial load and moment load in all directions. At the same time, the size of the inner and outer rings is minimised, especially in the extremely thin form, which is close to the limit of the small size, and the high rigidity makes it ideal for a wide range of applications such as the articulated or rotating parts of industrial robots, the rotating tables of machining centres, the rotating parts of robots, precision rotating tables, medical instruments, measuring instruments and IC manufacturing equipment.