Abstract: It is easy to form a contradiction between the drainage of pumping stations based on people’s livelihood and water intake of waterworks.In particular,the actual problems such as whether the drainage station can be built within the quasi-protection zones of the water intake or how far the distance between the two needs to be scientifically demonstrated.Physical model is used to study the influence of the pumping station drainage on the downstream water plants in the tidal reach of the Yangtze River.A qualitative simulation experiment using potassium permanganate tracer and the semi-quantitative simulation experiment measuring conductivity with NaCl solution is carried out.The results show that potassium permanganate qualitative tracing could observe the flow trace of drainage water at different Yangtze River flows,with the increase in the Yangtze River flow,the flow trajectory discharged by the pumping station deflected regularly from the deep trough to the onshore direction due to the current jacking.The semi-quantitative simulation experiment data show that the influence of drainage water body on the conductivity of water intake shows an obvious regular pattern of two rises and two falls.And because of the superposition effect,the latter peak is higher than the previous peak.When the drainage flow of the pump station is 21 m~3/s,the maximum dilution ratio of the conductivity of the water intake is 1.58%,2.46%and 2.12%respectively under the three stages of Yangtze River flow from large to small.When the drainage flow of the pumping station is 14 m~3/s,the maximum dilution ratio of the conductivity of the water intake is 0.92%,1.31%and 0.94%respectively under the three stages of Yangtze River flow from large to small.Only the drainage flow of the pumping station is 7 m~3/s,the drainage flow had no impact on the water quality of the water intake.The pumping station drainage had the greatest impact on the water intake when the middle flow of the Yangtze River and the pumping station drainage flow are the largest.It can be seen that the pumping station drainage has the greatest impact on the water intake when the balance between the Yangtze River flow scouring dilution and the water trace direction is realized.In addition,the physical model can be applied to the study of pollutant diffusion effects in the environmental field.