Abstract: The SrTiO₃ thin film used as oxygen sensor was prepared by Sol-gel method. The Fe ion content in Fe-doped SrTiO₃ thin film is 10mol%, 15mol%, 20mol%, 25mol%, 30mol%, respec-tively. All samples were measured in the temperature range of 600℃-800℃ and PO₂ region from 0 to 0.25× 105Pa.The results show that the thin film exhibit P-type conduction. It is found that when the Fe ion content is between 20mol% to 25mol%,the resistance of SrTiO₃ fells obviously and it is independent on temperature from 600℃ to 800℃.The results can be explained according to the defect chemistry equations.