Abstract: This paper presents an approach of water utilization networks design by the combination of water pinch analysis and mathematical programming. Water pinch analysis can discover the operational bottlenecks so as to identify the minimum freshwater consumption and determine the elementary rules for water utilization networks design based on the understanding for water using process. Based on the water pinch analysis, a superstructure of water utilization networks can be built which involves only feasible and better retrofit options. Then an improved mixed integer nonlinear programming (MINLP) model for the network superstructure is proposed which considers the freshwater usage, wastewater discharge and reuse of process. The approach overcomes the defect that water pinch synthesis designs the water utilization networks with loop and prevents the case that the superstructure is so large that it is difficult to solve. At last, the problem can be solved with the general algebraic modeling system (GAMS) to acquire the optimal design scheme of water utilization networks. Case study illustrates that the combined method could identify the minimum freshwater consumption and determine the reuse structure concisely and practically by water pinch analysis and reach global optimum of water utilization networks by mathematical programming.