Abstract: The algorithm of assistant decision-making for static security analysis is described in the paper. Based on the conventional sensitivity method, a new method is introduced to calculate outage distribution factors and the outage sensitivity which can reflect the relationship between node power and branch power after an element is out of service. Assistant decision-making for static security analysis can be easily acquired with the help of equal and opposite quantities in pairs for strategy of outage sensitivity. The assistant decision- making can satisfy the requirement of on-line application. Simulation results on real power system show that the proposed method is effective.