C-axis oriented YBa₂Cu₃O_(7-δ) (YBCO) thin films were grown on Al₂O₃ (alumina and R-plane sapphire) substrates by a pulsed laser deposition method. The crystallinity of the CeO₃ buffer layer on sapphire substrate exhibit a strong dependence on the deposition temperature, resulting in the growth of a-axis orientation at 800 ℃. The superconducting properties of YBCO thin films on Al₂O₃ substrates showed strong dependence on both thickness and crystallinity of the CeO₂ buffer layer. Critical temperature of YBCO film on alumina substrate was ∼83 K. In the case of R-plane sapphire substrate.