Abstract: In order to realize the quantitative evaluation of railway transportation safety risk, support the hierarchical management and accurate early warning of railway transportation safety risk, this paper proposed a quantitative evaluation model of railway safety risk based on the theory of layers of protection analysis, defined the concept of protection layer, which is the manual or automatic detection and monitoring means adopted in all links of railway transportation production. The risk frequency was determined by the natural frequency of the risk initial event and the failure frequency of the protective layer, and the loss caused by the risk was quantitatively evaluated from three aspects: direct economic loss, casualties and interruption of driving, to make sure the risk value can be calculated accurately. The risk assessment of turnout failure in a freight station was used as an example to conduct model evaluation test. The results show that the model can quantitatively evaluate the safety risk of railway transportation, and ensure the evaluation quality.