SiO2-doped and pure ZnO thick film gas sensors were prepared by using screen printing technique and tested for their methanol and ethanol gas sensitivity. Morphological properties of the thick film are studied by using field emission scanning electron microscopy ( FESEM). The results show that SiO2 -doped is quite effective in restraining the growth of ZnO grains. SiO2-doped enhanced the sensitivity of thick film ZnO gas sensor to methanol and ethanol gases at the operating temperature of 400 ~ 450 ℃. However, the sensitivity of this thick film ZnO gas sensor to methanol and ethanol gases was restrained, at the operating temperature between 200 ℃ and 350 ℃. Furthermore, the response time of the SiO2-doped ZnO film was always longer than that of pure ZnO. Finally,the sensitive mechanism of the thick film gas sensor was analyzed and discussed.%利用丝网印刷技术，制备出掺入SiO2和未掺入SiO2的ZnO厚膜气敏传感器，测试对甲醇和乙醇的气敏性能，并用场发射扫描电子显微镜(FESEM)来分析表征气敏膜的微观形貌。结果表明SiO2的掺人有效地抑制了ZnO晶粒的长大。在工作温度为400～450℃时，SiO2的掺入显著提高了ZnO厚膜气敏传感器对甲醇和乙醇的敏感度，而在工作温度为200～350℃时，SiO2的掺入明显抑制了ZnO厚膜气敏传感器对甲醇和乙醇的敏感度。另外，SiO2的掺入使气敏传感器的响应时间显著延长了。最后，讨论了厚膜气敏传感器的气敏机理。
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