Abstract: Existing gas monitoring of fixed place and mobile situation in coal mine underground is realized by safety monitoring system and intelligent gas inspection system separately. Monitoring data in the two systems has no relevance. Application status of the two systems was analyzed as well as existing problems. A viewpoint was proposed that data of the two systems could be fused, thus gas monitoring in fixed places and mobile gas detection in operation places could be supplementary to each other, so as to realize underground gas monitoring with no dead space. Main problems in data fusion of the two systems were researched, which were unifying monitoring data property, position information, data storage mode and data expression mode, and unifying monitoring data, time information and space information. Key technologies of the data fusion were also researched including main data management platform, accurate positioning of underground and a map of GIS.