Abstract: An operational safety evaluation method of straddle monorail vehicle system was proposed based on cloud model and CRITIC method. According to the structure and function of the straddle monorail vehicle system, the reliability index system of the straddle monorail vehicle was established, and the weight values of the reliability evaluation index were determined by the improved CRITIC method. The cloud model expression of the reliability evaluation index of the straddle monorail vehicle system was obtained by the virtual cloud. The similarity analysis between the new cloud of the comprehensive reliability index of the straddle monorail vehicle system and the cloud model of the reliability evaluation set was conducted to judge the operation status of the comprehensive cloud model of the straddle monorail vehicle system. The results show that the bogie index, air brake index, train network index, auxiliary system index and the integrated cloud model of the vehicle system are all in the ″main function″ state, which is in good agreement with the actual operation state of Chongqing rail lines. The system reliability evaluation method based on the cloud model and the improved CRITIC method can accurately evaluate the daily operation status of the straddle monorail system in Chongqing.