Traffic accidents have been closely concerned by the society, and the serious traffic accidents caused by vehicle and guardrail collisions are one of the main manifestations. However, the research in the field of vehicle and guardrail collisions is mainly limited to the waveform guardrail on the expressway, and there is little research on the urban road guardrail, especially in the secondary damage caused by guardrails field. Moreover, the collision between vehicle and the rectangular guardrail of city road is easy to form thin-walled long rod, and it penetrates the driver's chest. To evaluate and analyze the injury results and mechanism of this phenomenon, a penetrating finite element model of chest bone characterized by Chinese human is established using the medical software (MIMICS) and engineering software (HYPERMESH). The model validation is mainly dependent on the corpse impact test. In addition, the software (LS-DYNA) is deployed to simulate the thin-walled long rod penetration. According to the analysis of the "PENETRATION," it is found that the cavity effect produced by the thin-walled long rod through the chest, and the degree of chest damage is related to the speed, angle, weight, and stability of the thin-walled long rod. The difference between the peak value of collision corpse experiment and simulation peak value is less than 5%, which implies that the model is reasonable. Besides, the simulation results also confirm the accident and medical diagnosis cases. As a common form of secondary injury in traffic accidents and a typical case of medical penetrating injury, the thin-walled long rod penetrating injury has important reference value for studies in both directions.