The electron beam curred(EBC) coating composed of epoxy-acrylates resin as oligomer have been used in vast area. The microstructure of the coating is closely correlated with moleculers structure the components and radiation dose during curing. The S-parameter of positron annhilation doppler broadening was measurred as a function of positron energy to study electron irradiation induced polymerization and crosslinking. The correlations of S-parameter with content, moleculers structure of reactive diluent, and irradiation dose were observed.