A dynamic diagnosis system ofminesafety based on multi-data fusion is designed by combining the advantages of cloud computing and the Internet of things. The system’s framework is built with a three-tier model, and the construction of the cloud computing service platform provides essential support for mass data storage, processing, and security diagnosis reasoning. Simultaneously, using the relational database SQL Server 2017 and the object-oriented language C# to complete the designof an expert knowledge base and reasoning mechanism, and establish the diagnostic scoring system in the way of weighted sum. Therefore, based on the logical matching and reasoning between the collected data and the safety rules, the dynamic diagnosis ofminesafety is realized.