Four-point contact ball slewing bearing is a kind of large-scale bearing which can bear axial force, radial force and tilting moment of force at the same time, always with mounting hole, lubricant hole, and seal device. So it can easily make the mainframe structure compact, and it is convenient to conduct circumgyratetion, manufacture, install and maintain. It is widely used in hoister transportation, mining, architecture, harbor machinery, shipping mechanism, radar machinery of high accuracy, and large-scale rotary devices on aspect of missile launcher.