Bearing isolator is a non-contact sealing form developed on the basis of compound labyrinth seal, which is composed of static ring and dynamic ring. The stationary ring has an oil return hole to prevent lubricant leakage. The moving ring rotates with the shaft by the driving ring, and forms a complex labyrinth path with the static ring to prevent the external pollutants from entering the bearing box. The bearing isolator is a permanent bearing protection device. The bearing isolator with the best performance is made of metal.