The electrical properties of poly-Si thin film transistors (TFTs) using rapid thermal annealing with various gate oxide thicknesses were studied in this work. It was found that Poly-Si TFT electrical characteristics with the thinnest gate oxide thickness after RTA treatment exhibits the largest performance improvement compared to TFT with thick oxide as a result of the increased incorporated amounts of the nitrogen and oxygen. Thus, the combined effects can maintain the advantages and avoid the disadvantages of scaled-down oxide, which is suitable for small-to-medium display mass production.