The invention discloses an evaluation system for a decomposition coordination-based large power grid operation key quantitative index system. The evaluation system is characterized by comprising a parameter collection module, a processing module, a judgment module and an analysis module, wherein the collection module collects operation parameters in a large power grid; the processing module is connected with the judgment module and used for performing data processing on the operation parameters to obtain processed data and sending the processed data to the judgment module; the judgment module is connected with the analysis module and judges whether a decomposition coordination method is adopted for analyzing the processed data or not according to the processed data; when a judgment result of the judgment module is that the decomposition coordination method is not adopted for analyzing the processed data, a global analysis method is adopted for integrally analyzing the safety, economy and superiority of large power grid operation; and when a judgment result is that the decomposition coordination method is adopted for analyzing the processed data, the decomposition coordination method is adopted for calculating the processed data and analyzing operation conditions of the global power grid according to power grid conditions of local regions.