Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8577, Japan Structural properties of ionomer aggregations in a mixture of 1-propanol (NPA) and water have been investigated using coarsegrained molecular dynamics simulations. To perform simulations of larger systems and longer time spans, the reduced spatial resolution of the bead representation was used as a coarse-grained model for the enhancement of the computational efficiency compared to all atomistic simulations. The dependence of NPA content on the ionomer structures was studied by systematically changing the NPA content in the system. The self-assembly behavior of ionomers into cylindrical bundle-like aggregates was observed for all NPA content solutions. The radius (thickness) of an ionomer bundle was also found to be in good agreement with experimental measurements. Formation of ionomer aggregations showed different behavior at each NPA content, although the ionomers aggregated into one cluster at all NPA contents.