The main function of hub bearing is to bear the load and provide accurate guidance for the rotation of the hub. It bears both axial and radial loads and is a very important component. The traditional bearings for automobile wheels are composed of two sets of tapered roller bearings or ball bearings. The installation, oiling, sealing and clearance adjustment of the bearings are all carried out on the automobile production line. This structure makes it difficult to assemble in the automobile factory, with high cost and poor reliability. In addition, the bearing needs to be cleaned, oiled and adjusted when the automobile is maintained at the maintenance point. The hub bearing unit is developed on the basis of standard angular contact ball bearing and tapered roller bearing. It integrates the two sets of bearings. It has the advantages of good assembly performance, omitting clearance adjustment, light weight, compact structure, large load capacity, lubricating grease can be installed in advance for sealing bearing, omitting external hub seal and avoiding maintenance. It has been widely used in cars and has a tendency to gradually expand its application in trucks.