The invention discloses a historical data-based power system stability fast judging method. The historical data-based power system stability fast judging method includes the following steps that: power grid historical operation data are collected, and statistics quantity is calculated; power grid real-time operation data are collected; fault stability degree indexes are solved for faults of power grid key nodes and power grid weak fault points; correlation analysis is carried out, so that fault feature variables of each sampling point are formed; and a stability degree index at a current time point is calculated, and power grid stability at the current time point is judged. According to the historical data-based power system stability fast judging method of the invention, the real-time stable performance of a power grid is fast judged according to power grid operation and fault data of power grid real-time operation data and a power system historical database; and calculation obtained results every time will be incorporated in the database, and the database is updated, and therefore, the historical data-based power system stability fast judging method of the invention has the advantages of low calculation complexity low and high calculation speed; and a time-domain simulation method is adopted to calculate the stability of a system, and the calculation results are incorporated into the historical data, ,and therefore, the method of the invention can accurately judge the stability of the power system.