A series of poly (2-alkoxy-1,4-phenylenevinylene)’s was synthesized by water-soluble precursor method. In this paper, three poly(1,4-phenylenevinylene) (PPV) derivatives were included, poly (2-methoxy-1,4-phenylenevinylene), poly(2-butoxy-1,4-phenylenevinylene) and poly (2-dodecyloxy-1,4-phenylenevinylene). These polymers were characterized using UV-visible, FT-IR spectroscopy and DSC, TGA thermal analyzer. The third order nonlinear optical susceptibilities of the polymers were determined using third harmonic generation (THG) method at 1907 nm, fundamental wavelength. Measured chi((3)) values are 10(-11) similar to 10(-12) esu order and as the side chain length is increased, the chi((3)) value is decreased because of the side chain effect on conjugation and of volume fraction.