[Objective] The infiltration laws of slope soil bodies under short-duration heavy rainfall were investigated to reveal the causes and mechanisms of geological disasters in order to provide a scientific basis for the formation mechanism, early warning, and prediction of geological disasters in the region. [Methods] Regarding the shallow flow-type landslide event induced by heavy rainfall in Wuping area, Longyan City, Fujian Province, on May 26—27, 2022, an in-situ artificial rainfall infiltration test was conducted at the typical landslide site of the geological disaster area. Systematic observations using monitoring devices such as soil moisture meters, tensiometers, pore water pressure sensors, and rain gauges were conducted. At the same time, finite element software was used to simulate the rainwater infiltration process under different rainfall intensities to deepen the understanding of the infiltration law. [Results] The increase in volumetric water content of the soil was greater near the surface of the slope and decreased with increasing burial depth. The infiltration rate of the slope was fastest at the foot and middle of the slope and slowest at the top of the slope. Under the impact of short-term intense rainfall, the pore water pressure increased gradually, peaked, and then stabilised. Notably, the pore water pressure at a distance of 120 cm from the slope surface was higher than that at the other two depths. This may be attributed to the lower permeability of the soil layer at this location, which resulted in a relatively stable water level. The numerical simulation results reflected this pattern effectively. [Conclusion] The infiltration process of the slope soil is extremely complex in the case of short-duration heavy rainfall and plays a crucial role in triggering geological disasters. Its infiltration characteristics are comprehensively influenced by multiple factors such as rainfall intensity, soil layer depth, and permeability.