Microdomain structures of ABC 3-miktoarm star terpolymers in three-dimensional space were investigated by dynamic density functional theory (DDFT). Analysis of DDFT demonstrates that the junction points are restricted to lie on the periodically spaced parallel lines formed by the mutual intersections of different domains at the strong segregation between distinct blocks. With the improvement of compatibility of one component with the two other components, the localization of junction points is changed to the tendency of distribution over intermaterial dividing surface between the domains. (C) 2003 American Institute of Physics.