Using the RNG k-ε turbulence model,this paper established three-dimensional hydrodynamic mathematical model to study on the characteristics of drag force of the orthogonal spur dike with toothed mixture embankment of the 12.5 m deep-water channel regulation phase II project in the Yangtze River under Nanjing.The mathematical model is validated well by the measured data of flow velocity,water level and drag force of tooth structure.The drag force characteristics of the orthogonal spur dike with toothed mixture embankment which varies with the change of flow velocity,water depth and dike length are studied using this model.Moreover,the axis distribution of drag force of the orthogonal spur dike with toothed mixture embankment is discussed.