针对路段型随机用户均衡模型,提出了将随机均衡状态下的加权平均出行成本作为交通网络效率的度量方法,应用泰勒中值定理,给出了基于该网络效率的需求脆弱性指标的敏感性分析,发现当起点出行需求量扰动不大的情况下,敏感性分析方法计算的需求脆弱性指标可以近似代替传统方法计算的结果.结果表明:需求脆弱性指标的敏感性分析方法是可行的,合理改善对该指标较为敏感的出行地区的交通出行量,可以提高整个路网的可达性,具有一定的普遍性和推广意义. According to the stochastic user equilibrium model of road segment, this paper proposes a weighted average travel cost under stochastic equilibrium as a measure of traffic network efficiency. The Taylor median theorem is applied to give a sensitivity analysis of the demand vulnerability index based on the network efficiency , We find that the demand vulnerability index calculated by the sensitivity analysis method can approximately replace the result of the traditional method when the demand of departure trip is not disturbed.The results show that the sensitivity analysis method of the demand vulnerability index is feasible and reasonable Improving the traffic volume in the travel area which is more sensitive to the index can improve the accessibility of the entire road network, which has a certain universality and promotion significance.