The phase separation between strong polar ionic conductive and apolar conjugated light-emitting polymers in light-emitting electrochemical cells (LECs) can be avoided with a novel luminescence copolymer EO-NV containing a rigid conjugated light-emitting segment-di (dimethoxy styrene) naphthalene and a flexible ionic conductivity segment-triethylene oxide on the skeleton chain synthesized using the Witting reaction. FT-IR, 1H-NMR, UV-Vis, GPC, etc. were used to characterize its molecular structure and to study its photoluminescence properties. The results showed that EO-NV has good solubility in common organic solvents such as chloroform, tetrahydrofuran, benzene, pyridine, etc., and has film-form processing properties. The maximum photoluminescence peaks of the copolymer in a chloroform and a solid film were 470 nm and 505 nm, respectively. EO-NV is a functional blue-green luminescent copolymer used for fabricating LECs devices by combining the control of the conjugation length and the processability of the polymer with ionic conductivity.