[Abstract] The upper reaches of the Yangtze River are mostly pebble bed load side beaches. By consulting the channel Atlas of Yibin Chongqing section of the upper reaches of the Yangtze River, the side beaches with different water surface slopes are designed by using the model similarity scale, and the maximum scouring depth of the river channel under the action of two different forms of side beaches is studied by using the method of theoretical analysis and flume test. It is found that in the same part of the same beach, when the hydraulic factors such as water depth are the same, the scouring depth increases with the increase of the test discharge; Under the same hydraulic conditions such as water depth and flow, the greater the slope of the adjacent surface of the beach, the greater the corresponding scouring depth. This paper establishes and fits the calculation formula of the maximum scouring depth of the straight section under the action of the edge beach in the upper reaches of the Yangtze River. The research results are of great significance for studying the scouring and silting change mechanism of staggered beach and maintaining the safe passage of channel in the future.