During main river closure of the Yangtze River at the Three Gorges Project(i.e.TGP),it was showed that the real-time information and forecast in hydrology and sediment played important roles in optimizing the closure scheme design,protecting the cofferdams during flood season,doing construction organization and making regulation.In terms of the contract about TGP,signed with China Three Gorges Development Corporation,Hydrology Bureau of Yangtze River Water Resources Commission has successfully completed all tasks concluded in the agreement and made outstanding contribution to the closure engineering.In the work as mentioned above,the bureau creatively used more advanced techniques in the world today,developed sediment monitoring system and hydrologic forecasting models suitable to the closure gap,and provided varied types of hydrologic information in time.This paper gives a brief introduction about origin of the tasks,the adopted technological approach and its measures,the achievements and its application etc.