A simple and effective synthesis method for the dissolved poly(1,8-diaminonaphthalene)(P18DAN) with multifunctionality is a main challenge. Herein, a strategy is reported for the facile synthesis of N-substituted carboxyl group poly(1,8-diaminonaphthalene) by an oxidative polymerization of the N-substituted carboxyl 1,8-diaminonaphthalene monomer, prepared by a nucleophilic substitution reaction using chloroacetic acid and 1,8-diaminonaphthalene as reactants in N,N-dimethylformamde (DMF) solution. The europium doped carboxyl modified poly(1,8-diaminonaphthalenen) was fabricated in acidic solution containing europium ions. Their structures were characterized by the spectra of FT-IR, NMR, UV-vis, XRD, XPS. Structural analysis indicates that only one amino group can participate in nucleophilic substitution reaction, and the interaction of N-substituted carboxyl Poly(1,8-diaminonaphthalene) (PNDAN) with rare earth cations occurs at the nitrogen atom of imine and carboxyl groups on polymeric chain backbones. The isolated five-membered ring and the conjugated six-membered structure are formed among Eu3+ ions and nitrogen atom and carboxyl group at P18NDAN chain. The emission wave will shift from 405 to 462nm comparison with P18DAN polymer, whereas the fluorescent intensity only causes slightly change.