The double row ball slewing bearing has three seat rings. The steel balls and isolators can be directly arranged into the upper and lower raceways. According to the stress conditions, the upper and lower rows of steel balls with different diameters are arranged. This kind of open assembly is very convenient. The bearing angle of the upper and lower arc raceway is 75 degrees. It can bear a great deal of axial force and overturning moment. When the radial force is greater than 0.1 times the axial force, the raceway must be specially designed. The axial and radial dimensions of the double row ball slewing bearing are relatively large and the structure is fastened. It is especially suitable for handling tower cranes, truck cranes and other loading machines that require medium or above diameters.