The optimum composition ratios of primary solute(p-terphenyl) and secondary solute(popop) have been investigated in order to fabricate plastic scintillator with higher light output and less radiation damage. The radiation damage induced by Y -irradiation depends on mainly the concentration of secondary solute. The spectral range of the luminescence was 400∼450 nm, its peak emission appeared at 415 nm. The transmittance and the light output were not changed by radiation damage up to 1 x 10⁴ Gy irradiation with ^(60)Co γ-rays.