Abstract: Qianshan River is a typical intercity border river in Guangdong-Hong Kong-Macao Greater Bay Area, and its drainage capacity directly inpacts the safety of Zhuhai and Zhongshan. Based on the historical data, the drainage pattern evolution in Qianshan River Basin is analyzed, and the existing problems of drainage pattern are analyzed from the aspects of water conservancy engineering, river bed evolution and underlying surface change. Aiming at the problems, from the "storage, block, hysteresis, guide, drainage" point, this paper puts forward the corresponding drainage treatment scheme, calculations and analyses the effectiveness of the scheme using one-dimensional hydrodynamic mathematical model. The results show that after the application of the proposed targeted treatment measures, the waterlogging and flood level of Qianshan intercity border River has decreased greatly, and the problem of poor drainage has been solved.