In view of the fact that bridge fires have posed an increasingly serious problem，the fuzzy comprehensive evaluation method is adopted to analyze the occurrence probability of vehicle fires in bridges in this paper． First，the risk evaluation index system of bridge fires is set up by taking into account all kinds of factors influencing the occurrence probability of vehicle fires． Then，the weight of each index is determined by combining the analytic hierarchy process (AHP) and the entropy weight，and the initial evaluation matrixes are also processed based on the gray fuzzy theory． Thus，an occurrence probability model of bridge fires is constructed． Because of the great similarity between bridge fires and tunnel fires，a frequency classification criterion of vehicle fires in bridges is set up by collecting the data of tunnel fires as the reference． Finally，the case analysis of a bridge is carried out，and the occurrence probability of a truck fire is obtained． The results show that the proposed model is feasible and applicable，so it can provide the decision-making basis for the fire-resistance design and safety maintenance of bridges．