Abstract: The plain river network area is supported by the water level of the outer river during the flood season,and it is often difficult for the regional waterlogged water to drain by itself. It is necessary to build a new drainage pumping station to solve the waterlogging problem.Taking Yanka Pumping Station as an example,according to the precipitation and underlying surface conditions in the drainage area,the average elimination method and the hydrological and hydrodynamic model method are used to determine the scale of the drainage pumping station in the plain river network area to meet the regional drainage requirements. According to this analysis,the traditional average elimination method and the new hydrological and hydrodynamic model method have their own advantages,and the combined use can scientifically and reasonably determine the design flow of the drainage pumping station,and provide water safety guarantee for the regional economic and social development. The research results can provide a reference for determining the scale of drainage pumping station in plain lake area.