Abstract: Soon after zongpingxi hydropower station was put into operation, the maintenance staff found the cracks along the stay vane in 1F, 2F, 3F water turbine in daily maintenance. From April 2, 2005 to January 16, 2007, the company carried out treatment for the three turbines six times, but new cracks formed soon. The company organized a special group to find the reasons to cause the cracks. Through in-depth analysis, they proposed to change the operating mode of production of certain working options, and good results were achieved.