Qinhe River inverted siphon is one of the important control engineering works in South to North Water Diversion Middle Route Project. Qinhe River is a wandering stream and is known as a little Yellow River. The thickness of fine sand in Qinhe riverbed is 13-20 m. It is very difficult to determine the depth of scour and the depth of inverted siphon, which directly determine the engineering safety, investment, flood control safety and other important issues, and so experimental study of movable bed model on the inverted siphon is very necessary. The test model was designed to simulate the prototype of water and sediment movement and river bed deformation of the model similarity theory, the sand of model must be able to meet the requirement of the evolution law of wandering of Qinhe River and could adapt to the needs of the running of the continuous scouring test and coke sand. The test used 3 kinds of working conditions to check the evolution law and scour depth of flood, less sediment concentration flood and channel forming discharge. Test results find out that the law of main stream, the maximum scour depth of the river under the flood is 11.54 m and the local maximum scour depth is 13.15 m.%沁河倒虹吸是南水北调中线工程重要控制工程之一。沁河下游为游荡型河流，河床细沙厚13～20 m，合理确定冲刷深度和倒虹吸埋深非常困难，但其直接决定工程安全、投资及防洪安全等，因此开展动床河工模型试验研究十分必要。模型设计采用模拟原型水沙运动及河床变形的模型相似理论，模型沙须能够满足模拟穿沁河段游荡性演变规律的要求，并能适应持续冲刷试验运行的需要，选用拟焦沙符合要求。模拟在3种工况（校核洪水、校核大水少沙洪水和造床流量）下的河道演变规律和冲刷深度，发现主流呈“大水走直、河势下滑”规律，校核洪水下河中最大冲刷坑水深为11．54 m，局部最大冲刷坑水深为13．15 m。
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