The invention relates to a distribution network early-warning method based on an improved Apriori algorithm, which belongs to the field of distribution network early warning of electric systems. The distribution network early-warning method has the characteristics of clear thought, simple and convenient algorithm, less workload and high execution efficiency. Aiming at the defects of the prior art, history data are mined by utilizing a data mining technique, and real-time data are monitored on line, so as to judge which indices possibly cross a line within a period of time in the future when one index crosses the line, and an early warning is given; the situation that only one index crosses the line at present is eliminated.