Abstract: Aimed at the phenomenon of voltage sag in the distribution network, a multi-index evaluation method based on comprehensive weight is proposed. Compared with the traditional methods, this method selects multiple evaluation indexes both from power supply side and electricity side, making evaluation results more comprehensive. It employs analytic hierarchy process (AHP) and the CRITIC method to calculate a new weight, giving full consideration to the deep inner relation between each evaluation index, as well as their relative importance, making evaluation results more reasonable; After multiple Monte Carlo simulation, the composite score of each node is calculated, and the sag vulnerability area intersection of weak nodes in the network is obtained. Finally the results of an example prove that this method can accurately and effectively identify weak nodes and weak area in network, and lays the foundation for voltage sag and control.