Aimed at the oil leakage problem of the sliding bearing comb labyrinth seal for the single stage high speed centrifugal blower in the coalfired power plant,according to the sealing requirements and the field working conditions,a magnetic mechanical seal was used to replace the original comb labyrinth seal.The theory calculation and structure design of the magnetic mechanical seal were carried out based on the sealing requirements.The actual operation shows that the designed magnetic mechanical seal can meet the sealing requirements of the sliding bearing of the single stage high speed centrifugal blower and solve the oil leakage problem of the equipment.