To explore the changes in topsoil structure and infiltration capacity under raindrop splashing and provide reference for predicting soil erosion conditions under raindrop splashing, this study explored the relationship between topsoil pore structure and permeability under rainfall conditions by using the raindrop splash experiment, soil infiltration experiment and synchrotron radiation CT scanning technology. The results showed that: 1) Raindrop splashing significantly reduced topsoil total porosity and permeability coefficient (P<0.05). The total porosity decreased by 20.64%, 36.05% and 44.88%, respectively, and permeability coefficient decreased by 15.69%, 40.42% and 71.77%, respectively, after the splashing of raindrops with diameters of 2.67, 3.39 and 4.05 mm. The fragmentation level of pores intensified after raindrop impact, leading to a more irregular pore shape and connectivity reduction. 2) The size, shape and connectivity of pores had significant effects on permeability (P<0.01), the larger the pores and the more regular the shape, the greater the impact on permeability. From the perspective of pore connectivity, the radius of connected pore throats and the porosity had the greatest impact on infiltration capacity. On this basis, a predictive model was established for permeability coefficient (K) in relation to the total porosity (P_T), macroporosity rate (P_lp), regular porosity rate (P_rp), connected porosity rate (P_cp), and pore throat radius (R_th): K=0.402P_T+0.104P_lp+0.1401P_rp+0.350P_cp+0.003R_th–0.415,R²=0.93, P<0.05. In conclusion, raindrop splashing alters the size, shape and connectivity of pores, leading to the disruption of pore structure and a decrease in infiltration capacity.