Abstract: The operation troubles of the main drive system of the piercing mill in Φ177 mm PQF continuous pipe rolling plant in recent years are summarized and analyzed and the key causes that restrict the longevity operation of the main drive system are found out, which are immoderately adjusted thrust bearing clearance on the first shaft of the reduction gears, high failure rate of the cross pin bearing of the link rod in the bottom position due to the influence of temperature and water, insufficient strength with the link rod alignment device.Some countermeasures are worked out based on the above problems, which are to optimize the axial clearance of the thrust bearing, take waterproof measures to the cross pin bearing of the link rod in the bottom position, shorten the oiling cycle, optimize the start up curve of the electric motor, reduce the impact to the drive system, redesign the link rod alignment device with higher strength.