The supramolecular interfacial polymerization induced at the interface of water and oil phases is scrutinized with a dissipative particle dynamics simulation method coupled with a stochastic reaction model. Our study shows that supramolecular interfacial polymerization still obeys the characteristics of second-order reaction kinetics. At different time points during polymerization, the number fraction distributions of molecular weight can be described by the Flory distribution. The simulations indicate that the principle of step-growth polymerization is still valid in supramolecular interfacial polymerization. Moreover, an appropriate concentration of the feeding monomers is necessary to promote a high degree of polymerization in the supramolecular polymers. The simulation results can act as a theoretical guide for achieving a better design of new supramolecular interfacial polymerization systems and for optimizing the synthesis strategy for supramolecular polymers with even larger masses.