The method of fuzzy comprehensive evaluation is a kind of evaluation method of groundwater quality based on fuzzy mathematics.The weight in fuzzy comprehensive evaluation occupies a very important position, and reflects the importance of various indicators, directly affects evaluation results. In order to avoid unreasonable aspects of traditional method, this article introduced the comprehensive weight method based on AHP and entropy to calculate weight. This method fully thought the experience of experts and information of each data and effectively avoided the subjectivity and blindness.The evaluation results show that the comprehensive weight method based on AHP and entropy is practical and reliable.