Abstract: Two monomers, 2,5-dimethyl-N,N′-dichloro-benzoquinonediimine and N,N′-dichloro-benzoquinonediimine, were prepared using 2,5-dimethyl-p-phenylenediamine and p-phenylenediamine as raw materials in NaClO solution, respectively. Then two novel π-conjugated alternating copolymers were synthesized via metal complex catalyzed polycondensation of the two monomers with 2,1,3-benzoselenadiazole in yields of 45.0% and 49.4%, respectively. The copolymers were characterized by UV-Vis, FT-IR and cyclic voltammogram. The results showed that the two copolymers have absorption band at 338, 462 nm and 338, 392 nm, respectively. The cyclic voltammogram results explained the electroactive properties of the two copolymers. The electroactivity of the copolymers after doped with iodine was also investigated.