Poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-co-1,4-phenylene vinylene) (MEH-R) and poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-alt-1,4-phenylene vinylene) (MEH-A50) containing phenylene vinylene (PV) unit and alkoxyphenylene vinylene (MEHPV) unit in the main chain were synthesized by the dehydrohalogenation and Honer-Emmons reaction using potassium t-butoxide, respectively. Single layer polymer light-emitting diodes (PLEDs) were fabricated with synthesized conjugated copolymers as emitting layers, and their emission properties were compared with PPV and MEH-PPV homopolymers. UV-Visible absorption and EL spectra of MEH-Rs were blue-shifted as increasing the amount of PV unit in the main chain. Color coordinates of single layer PLEDs made with the conjugated copolymers were compared with those of standard red, green, blue, and white established by NTSC. Color coordinates of single layer PLEDs made with MEH-Rs and MEH-A50 were shifted from red (MEH-PPV) to green region (PPV) as increasing PV unit in the main chain.