It solves the complex structure and difficult processing of the existing seal device for the bearings of cooling drive device for vehicles. With major shaft and belt wheels on the cooling drive device, this seal device is set at the end face of the belt wheel, comprises a seal washer embedded outside the seal cover on the major shaft, said seal cover fixed with the inner ring of the bearing and the major shaft, seal washer fastening with the belt wheel, seal cover and seal washer locking with each other with the gaps forming into a labyrinth seal. It has fine anti dust and water proof performance with reduced friction noise and heat. It is convenient for loading and unloading with low cost.