The market has more and more stringent requirements for various mechanical equipment and instruments using rolling bearings, and the requirements for the conditions and performance of bearings are also more and more diversified. In order to select the most suitable bearing from a large number of structures and sizes, research is required from multiple perspectives. When selecting a bearing, the bearing structure is generally determined by factors such as the arrangement, installation and disassembly of the bearing as a shafting, the allowable space, size and market of the bearing. Second, bearing sizing is determined by comparing the design life and endurance limits of the various machines that use the bearing. When selecting bearings, only the fatigue life of the bearing is often considered, and the grease life, wear and noise caused by grease aging also need to be fully studied. In addition, according to different uses, it is necessary to select bearings with special design requirements for accuracy, clearance, cage structure, grease, etc., but there is no certain order and rules when selecting bearings. It is especially practical to give priority to the condition, performance and most relevant matters of the bearing.