本文根据扩建管网的特性，构造了直接以管段直径为求解变量的优化设计目标函数，利用约束条件的水力特点，采用了优化效果明显的广义简约梯度法（ＧＲＧ）进行计算，并通过目标函数变换，一次性解决了求解管径标准化的难题，并通过了实例验证。 Based on the characteristics of the expanded pipe network, this paper constructs an optimization design objective function that directly takes the pipe diameter as the solution variable. Using the hydraulic characteristics of the constraint conditions, the generalized reduced gradient method (GRG) with obvious optimization effect is used to calculate and pass the objective function. The transformation solved the problem of solving the standardization of pipe diameter at one time, and passed the example verification.