Use of rolling bearings of various mechanical devices, equipment and other properties of the increasingly stringent market requirements, the conditions required for bearing performance are becoming increasingly diverse. In order from a large number of structure, size, choose the most suitable bearing, we need to be studied from various angles. When selecting bearings in general, be considered as a shaft bearing arrangement, installation, ease of disassembly, the bearing space allowed, market size and bearing, etc., substantially determine the bearing structure. Secondly, while the use of comparative study of the various kinds of mechanical bearing design life and bearing different endurance limit, while the decision bearing size. When selecting bearings, often indulge in only consider the bearing fatigue life, about the life of the grease from the grease aging occurs, wear, noise, etc. also need to be fully studied. Furthermore, according to different uses, it is necessary to select the accuracy, clearance, cage structure, grease, etc. requirements, specifically designed bearings. But the choice of bearing no certain order, rule, priority consideration is the condition of bearing the required performance matters most in connection, it is particularly practical.