The brake safety of articulated train is the focus of the road freight transport industry. Brake chamber is an important component of the brake system in articulated train, whose performance has a significant impact on the vehicle braking performance. In order to improve vehicle braking performance, the dynamic characteristics of the brake chamber with pressure change were analyzed based on the model of the brake chamber and the brake drum assembly. By changing different specifications of rear axles’ brake chamber in tractors, the static and dynamic braking performance were analyzed. The results showed that the larger the bearing area of brake chamber, the better the braking performance of articulated train. Proposed suggestions on how to select the specification of brake chamber in articulated train were made and the research results provided technical reference for the design of the articulated train braking system.