Abstract: Investigation result shows that for the running KDY pump sets, such defects are existed as the leakage of lubricant oil, too big clearance at the shaft alignment, difficult to seal off the pump for repairing purpose, easy to wear down for the bearing and bearing insert. Relative improvement is presented to the originaldesign of the pump sets. The authors consider that the efficiency of the improved KDY pump sets is going up from 65% to 80%, the leakage amount of lubricant oil per month is down to 4kg, which elongate the service life of the thrust bearing and bearing insert.