The invention discloses a method of automatically analyzing fundamental reasons of index fluctuation. The method includes: receiving original data, which are configured by a user, by a data input module, extracting operation management data therefrom, and sending the same to an index construction module and a data processing module; constructing dimensions used for data analysis and indexes, whichcorrespond to the dimensions, by the index construction module according to the operation management data, and sending the constructed dimensions and the indexes, which correspond to the dimensions,to the data processing module; after the data processing module receives the dimensions, the indexes corresponding to the dimensions and the operation management data, analyzing change quantities of dimension values of all the indexes according to the dimension values corresponding to the indexes in an associated manner, selecting indexes, which correspond to a preset number of dimension values ofwhich change quantities are largest, as the reasons of index fluctuation, and sending the reasons of the index fluctuation and corresponding data to a data output module; and after receiving the index fluctuation reasons and the corresponding data, generating the same by the data output module according to a preset output mode, and outputting an index fluctuation reason analysis report.