In order to construct an accident classification theory that conforms to the characteristics and actual situation of urban rail transit operation in China, and to specify the detailed requirements for the classification of safety accidents in urban rail transit operation, by analyzing the current status of safety accident classification in relevant authorities and operating companies, some accident classification methods were summarized and proposed in two dimensions of hierarchical structure and classification standards, including single-level and double-level, as well as consequence, enumeration and combined accident classification methods. The advantages, disadvantages and applicability of different classification methods were compared and analyzed. At the same time, from the perspective of selection and evaluation of accident classification methods, an accident classification system that can be used to evaluate the integrity and effectiveness of the classification methods was proposed. The result shows that the single-level consequence-based classification method is more suitable for industry authorities, the multi-level enumerated and multi-level combined type are more suitable for operating companies; the accident classification system should include at least three levels of damage level, impact level and phenomenon level, and the corresponding severity of accident consequences is decreasing in turn.