Objective To study influencing factors of renal blunt impact injury by using finite element (FE) method. Methods Based on CT images of the kidney, the kidney FE models for different age groups were constructed. The renal blunt impact test was reconstructed, and the influence of kidney material constitutive parameters, kidney tissue structure, kidney size, impact position and impact velocity on injury severity were analyzed. Results Under the same impact condition, the stress of renal cortex decreased with the kidney mass increasing, and increased with the impact velocity of the hammer increasing. The renal capsule had a certain energy absorption effect, so as to reduce the kidney stress. When the kidney was impacted, the stress of renal cortex under side impact was significantly higher than that under frontal impact. Conclusions Compared with viscoelastic constitutive model, Mooney Rivlin material constitutive model is more suitable for FE evaluation on renal injury severity. The renal injury decreases with the kidney mass increasing. The increase of impact velocity will intensify the renal injury severity. Renal capsule will reduce renal injury to a certain extent, so the existence of renal capsule structure must be considered in FE modeling of the kidney. Compared with frontal and rear impact, the renal injury severity is greater when the kidney is impacted from the lateral side.