As a new branch of process integration system, mass exchange network (MEN) has the dual benefits of improving resource utilization efficiency and reducing environmental pollution. At present, the typical superstructure model has been well applied in MEN optimization, but the fixed arrangement of superstructure limits the flexibility of heat exchanger matching and the expansion of solution domain in the model. A new unstructured model with shunting nodes was proposed. The matching mode of mass transfer unit was quantified in the form of nodes, the free matching of mass transfer unit on the stream strand was realized and the flexibility of unit matching was enhanced. At the same time, considering the appearance of diversion in practical engineering, the diversion form of mass transfer unit was expressed by the number of groups and branches, which further expanded the solution range of the model. Finally, through the analysis and calculation of two actual MEN examples, the effectiveness of the unstructured model with split nodes was verified.