With the rapid development of the distribution network, the requirements for the stability of the distribution network are becoming higher and higher. However, due to the high complexity of the equipment and the influence of external factors, the failure of the distribution network may occur. In view of the problem that the distribution network equipment usually fails at the weak point, the concept of weakness degree is proposed to quantify the weak point. At the same time, in order to judge the weakness degree of the weak point, the distribution network weakness degree is set equal to the value of the support in the FP-Growth algorithm. The Kulczynski metric is then used in conjunction with the imbalance ratio to verify the strong correlation and significance of the association rules. The effectiveness of the method is verified by examples and actual operation conditions, which provides support for the analysis and detection of weak points in the distribution network operation.