The invention discloses a comprehensive pre-warning method based on a three-level multi-dimensional KPI system. The method includes: building the three-level multi-dimensional KPI system and a KPI algorithm and performing KPI pre-warning. The method has the advantages that the KPI system which can represents power grid operation states is built according the 'safety, economy, high quality and environmental protection' requirements of power system operation, the piecewise linear average normalization algorithm of KPI states is provided, the problem that data of different magnitude orders cannot be compared is solved, the comparison problem (for finding out which one is more serious) of multiple KPIs under the same state (such as pre-warning) is solved at the same time, and quantization of power grid operation state is achieved.