Abstract: Pinch analysis is now the main method to synthesize mass exchanger networks,usually minimum external lean stream flow-rate as objective.The capital cost could not be considered in the network analysis or it is difficult to take capital cost into consideration.With the deficiency of pinch analysis in mind,this paper presents a method for synthesizing the mass exchanger networks considering not only operating cost but also capital cost by using Genetic-Alopex mixing algorithms.According to the peculiarity of Genetic-Alopex algorithms and mass exchanger networks,a mathematical model for mass exchanger networks synthesis is developed.The model uses the total annual cost as objective.A simplified capital cost law is used for determining the number of stages required,which is then converted to a capital cost.The solving process for mass exchanger network synthesis by using Genetic-Alopex algorithms is introduced.This method is applied to a coke-oven gas-sweetening examples to contrast with the pinch technology.The examples computed by Genetic-Alopex algorithm show that the total annual cost is lower though the operating cost is sometimes higher.