Magnetic grease rotary sealing device used in a certain type of large capacity evaporative cooling motor has characteristics of split structure,high line speed,large diameter and shaft diameter,and etc.In order to test the sealing pressure of the magnetic grease rotary sealing device with split structure,test platform was built.The effects of pole teeth gap and line speed on the sealing pressure of the device were researched through measuring the sealing pressure in pole teeth gap of rotary shaft and inside cavity by pressure sensors.The results show that the distribution rule of sealing pressure of each track of pole teeth does not follow the theory value.The greater the pole teeth gap,the higher the sealing pressure in this track of magnetic grease seal.Within a certain range,line speed has little effect on the sealing pressure of each track of magnetic grease seal