Abstract: During the use of GSB-L high speed pump in the styrene unit, leakage of the lubricating oil, washing liquid and raw benzene occurred many times, which affected the normal production. Through analysis, it is found that the failure is mainly caused by mechanical seal failure. For this problem, shortcomings of the structure are analyzed and transformations are made. Finally, the effectiveness of the transformation is verified. It solves the leakage of high speed pump, prolongs the maintenance cycle of the equipment and reduces the production cost.