本文通过对城市交通系统各组成单元可靠性的研究，从系统网络全局出发，以单元可靠度作为控制参数，对交通系统网络的可靠性进行研究。文中指出了震后救护队的最佳选址以及需要改建、加固的路段等，从而为震前交通系统的防灾规划提供理论依据。 Based on the study of the reliability of each component of the urban traffic system, this paper starts from the overall situation of the system network and uses the unit reliability as the control parameter to study the reliability of the traffic system network. The paper points out the best location of the ambulance team after the earthquake as well as the need to reconstruct, strengthen the sections, etc., so as to provide a theoretical basis for disaster prevention planning before the earthquake traffic system.