Tungsten oxide (WO3) thin film has been prepared on a porcelain tube with gold comb-type electrodes by using a sol-gel technique with WCl6 as precursor. The X-ray diffraction and X-ray photoelectron spectrum results indicate the crystallization of tungsten oxide occurs at temperatures higher than 500 degreesC. The sensing characteristics of the thin film sensor to trimethylamine were measured. A low-temperature, high sensitivity, excellent selectivity, quick response and recover of thin film sensors to trimethylamine were found.