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The lightweight design of railway vehicle components using fiber reinforced polymers (FRPs) has become a research hotspot due to the strong need for energy saving and environmental protection. This paper aims to evaluate the impact damage behavior of a carbon fiber reinforced polymers (CFRP) protection suspender, which is a component on railway vehicles to prevent the falling joist and bolster from touching the rails and to avoid the derailment of trains. A finite element (FE) model of the CFRP protection suspender, which considered varying bolt preloads was established in ABAQUS/Explicit. The bolt preload was successfully applied around the installation holes on the protection suspender by deliberately reducing the local temperature of the bolt shank to create shrinkage. The impact behavior of the protection suspender was then analyzed, and the impact-induced damage was governed by the Continuum Damage Mechanics (CDM) models, which include both intra-laminar damage and inter-laminar damage. The low-velocity impact response of the CFRP protection suspender was investigated with the lay-ups of [0]10 and [0/90/0/90/0]S under different bolt preloads (i.e. 0, 5 and 20 kN). The results showed that the vulnerable positions of the protection suspenders included the contact edge between the protection suspender and the impactor, the curved corner of the suspender, and the areas around the bolt holes. In addition, the protection suspender with the lay-up of [0]10 had better impact resistance than that with the lay-up of [0/90/0/90/0]S. By applying different preloads, it showed that the increase of bolt preloads could help to prevent the occurrence of crack damage around the installation holes, thus improving the structural safety when subjected to low-velocity impact. The present simulation results offered great value for the lightweight design and structural optimization of a protection suspender on railway vehicles that had to survive from sudden impact loads in service.