Disclosed is a system for real-time expression of a semantic mind map and its operation method there for. The system includes an association matrix and a focus associated operation module, the association matrix is connected to the focus associated operation module. The association matrix includes a start node, a direct associated module, an indirect associated module, a weakly associated module, a superscript module, or the like. The focus associated operation module includes a focused node and focus associated nodes, or the like. When the present disclosure is applied to a search engine including a cross-database search engine, a search result service interface is in real time expanded, thus being used to help a user better identify and discover relevant documents of interest.