Weir flow measurement is an important content for safety monitoring of hydraulic buildings, and it is of great significance to strengthen the seepage monitoring of hydraulic buildings to ensure the safety of hydraulic buildings and feedback design. Based on the basic principles of optimal design of engineering structures and the theory of structural reliability, this paper uses nonlinear planning to optimize the structural design and flow calculation method of water-measuring weir in water conservancy canal system, and analyzes the hydraulic characteristics of the optimized water-measuring weir through numerical simulation, which verifies the effectiveness of the proposed method. The simulation results show that the influence of the new trapezoidal water-measuring weir with different orifice heights on the outflow over the weir gradually decreases with the increase of the total head in front of the weir, and the fitted flow equations are concise, easy to use and highly generalized, with an average relative error of 2.55%. At the same time, the average relative error of the flow and water depth of the U-shaped channel triangular profile weir is 0.22% and 5.76%, respectively, and the flow measurement accuracy of the long-throat channel optimized by the method of this paper is also controlled within 6%, which is in line with the flow measurement requirements of the water measuring channel, which indicates that the simulation results have a certain degree of reliability, and can provide a reference basis for the optimization of the design of the engineering structure of the water measuring facilities.
