[Objective] The internal deposits of collapse hill is the main material source of erosion. This paper aimed to reveal the infiltration regularity in that hill, and to explore the erosion mechanism on collapse hill by studing the infiltration process.[Methods] Field experiments of infiltration were conducted in site of Liantanggang collapse hill in Wuhua County of Guangdong Province using a self-made double circle infiltration device and soil moisture were measured with PR2/6 profile probe.[Results] (1) Soil steady infiltration rate of colluvial cone was between 0.58~2.41 mm/min with an average value of 1.37 mm/min.The average infiltration rate of channel soil was up to 5.58 mm/min. The infiltration process was dominated by gravity flow and soil structure was stability. (2) The infiltration rate showed a negative exponential power function relationship with infiltration time as the dependent variable, which conformed to Kositakov model. (3) The higher initial moisture content, the faster wetting front moved, meanwhile, the deeper of affected region, and its depth went down to 600~1 000 mm or even more when infiltration rate attained steady state. (4) The sectional moisture content showed a varied decline from profile top to bottom as affected by the heterogeneity of the soil.[Conclusion] The maximum depth of instable deposits in collapse vulnerable mount is at least 600~1 000 mm or even over 1 000 mm. Heterogeneity of colluvial cone soil can resist infiltration and form a stagnant water layer, which can potentially lead to subsurface erosion and hence has a great impact on erosion process of collapse hill. Therefore, the colluvial cone of that hill should be the focus of permeability study.