The invention provides a method and apparatus for obtaining hierarchical information of planar data. The method comprises mapping at least one data item from a same data set in the planar data to at least one node in a tree structure formed by a structured terminology system. The method also comprises obtaining at least one sub tree structure in the tree structure, each of the at least one sub tree structure taking the at least one node as all of its leaf node. The method also comprises selecting a target tree structure from the at least one sub tree structure and obtaining hierarchical information in the target tree structure. An apparatus corresponding to the above method is also provided. With the above method and apparatus, hierarchical information of data items may be obtained from planar organized data to facilitate subsequent and further analysis and management.