The main function of automobile hub bearing is to bear load and provide precise guidance for hub rotation. It bears both axial load and radial load. It is a very important component. Traditional automobile wheel bearings are composed of two sets of tapered roller bearings or ball bearings. The installation, oiling, sealing and clearance adjustment of bearings are carried out on the automobile production line. This structure makes it difficult to assemble in automobile factory, high cost and poor reliability, and the bearings need to be cleaned, oiled and adjusted when the automobile is maintained at the maintenance point. Hub bearing unit is developed on the basis of standard angular contact ball bearing and tapered roller bearing. It integrates two sets of bearings. It has the advantages of good assembly performance, eliminating clearance adjustment, light weight, compact structure, large load capacity, pre-loading grease for sealed bearings, eliminating external hub seal and avoiding maintenance. It has been widely used in cars. There is also a trend to gradually expand the application of trucks.