This paper aims to reveal the damage mechanism of urban and rural road systems in the southwestern mountainous areas in China in multi-disaster scenarios, and attempts to improve the reliable services capacity of road network in the disaster-prone areas. By selecting the Kangding section of the Dadu River Basin in the typical southwest disaster-prone zone, and by applying the complex network and computer simulation analysis method, it establishes the regional road network model and the multi-disaster interference simulation mechanism, and considers the overall connectivity and high-efficiency connectivity as the index system. The multi-disaster scenario simulates the reliability dynamic response law of road network in simulated disturbance. The empirical findings show that the reliability of urban and rural road network in the disaster-prone zone of southwestern mountainous areas is affected by the geographical location of critical road sections and geological disaster points, and the critical sections of different grades demonstrate the characteristics of cluster distribution. Based on these findings, this paper proposes some relevant countermeasures.