Abstract: To address the limitations of the traditional reliability analysis methods in analyzing the reliability of EMUs traction drive system, this paper performed reliability analysis based on Dynamic Bayesian Network (DBN). The paper established the dynamic fault tree of EMUs traction drive system, and mapped it into a DBN according to the DBN transformation rules, considered the dynamic characteristics and maintainability of EMUs traction drive system, used the forward inference of the DBN to obtain the dynamic change law of system reliability and availability with service time, and identified the weak links of the system by reverse inference. The analysis results showed that the DBN can comprehensively portray the dynamic characteristics and maintainability of the traction transmission system, effectively identify the system weaknesses, and provide a reference basis for operational risk assessment and reliability evaluation.