The prevention and control of concrete dam cracks is a key research topic in the design and construction of concrete dam engineering.The location and quantity of concrete cracks in each project are different,and the causes of cracks are also different.Only by analyzing the causes and hazards of cracks can corresponding measures be taken to prevent and solve them.In this paper,the causes and hazards of cracks on the pier and weir surface of an overflow dam of a riverbed hydropower station are analyzed in detail,and the crack treatment scheme and subsequent preventive measures are put forward.The cracks on the gate pier and weir surface of the overflow dam of the power station have been closed after treatment,and no new cracks have been found in the subsequent concrete pouring.At present,the project has been in safe operation for more than ten years.