<p>High-speed train brake pads typically utilize a multi-friction-block and triangle support structure to manage the substantial friction heat generated during high-speed braking. However, under low-speed, strong friction conditions, friction-induced stick–slip vibration (FISSV) is prone to occur, which can destabilize the braking system and compromise operational safety. To address this issue, a novel nonlinear dynamic model for high-speed train braking system was proposed, and this model precisely describes the characteristics of brake pad multi-friction block and triangle support structure. The model comprehensively considers the wheel-rail-braking coupling effect, an exponential Stribeck friction model, and the uneven distribution of normal forces across the friction blocks. Based on this model, nonlinear dynamic simulations were conducted to systematically analyse the dynamic characteristic of the brake pad at various hierarchical levels—from a single friction block and a triangle support-friction block unit to the entire assembly—under normal operating conditions. This analysis revealed the evolutionary pattern of the nonlinear dynamic behavior of the braking system as the brake disc transitions from periodic to stick–slip and subsequently to chaotic motion during the slip phase. Furthermore, to examine the typical failure mode of local friction block detachment, a dynamic model for a detached friction block was developed. A comparative analysis was performed to assess the impact of local friction block detachment on the dynamic behavior, stability, vibration intensity, and chaotic characteristics of the remaining friction units and the overall system. The results demonstrate that the proposed dynamic model of the braking system for high-speed trains effectively reproduces the complex nonlinear dynamic behaviors observed during low-speed friction braking. The friction radius of the friction blocks and their arrangements on the triangle support(TS) units significantly influence their vibrational stability and intensity; friction blocks at specific positions exhibit superior vibration characteristics. The local detachment of a friction block from the brake pad alters the system’s coupling and load distribution, causing significant changes in the vibrational behavior of the remaining friction units and the overall brake pad. This can lead to a reduction in the chaotic region for some units while potentially increasing the overall vibration intensity. This work establishes a nonlinear dynamic analysis model for the braking system of high-speed trains, incorporating the structural features of the multi-friction-block of brake pad. It provides an effective method for the accurate assessment of the nonlinear dynamic behavior of the braking system and offers theoretical support for the optimal design, condition monitoring, and fault diagnosis of braking systems, particularly in relation to friction-induced vibration and noise(FIVN).</p>