Abstract: Dahuofang hydraulic project has a multiple purpose of flood prevention, irrigation, public and industrial water supply, hydropower etc. During thirty years operation, the annual benefit exceeded the designed index. The excellent art of construction resulted in a small settlement of the earth dam. The total settlement of core wall during the construction period and operation perion was 22cm, while the settlement on berm was 13.4cm. The phreatic line in core wall was still 18m lower than calculated phreatic line, the stationary phreatic line has not yet been formed. The structures resisted against earthquake with intensity of (VI) degree harmlessl"-during Haicheng earthquake of magnitude 7.3 in Feb. 1975. The sediment in reservoir had been measured and was 35 Mm3 up to date, corresponding to 47% of designed 30 years sediment. The concrete structures suffered freezing-melting cycles under northern climate and no destroying or ageing feature were inspected withstanding flood discharge scouring.