[Background] Collapse mound,called Benggang in Chinese geomorphic pictograph, has been known to describe a kind of erosion phenomenon in hilly and mountainous area among subtropical and fractional tropical climatic zone of south China that gully head collapsed, transported and developed a deep-cut shape, concave-deforming deep-seated failure landform. [Methods] To reveal the effects of collapse mound erosion on soil available nutrients and stoichiometry ratios, we chose 3 collapse mounds of slight, moderate and strong erosion intensities in Huangniken collapse mound groups of Changting County of Southwest Fujian as research object. Soils at 0-10 cm, 10-20 cm and 20-30 cm in 4 positions of upper catchment, collapsing wall, colluvial deposit and channel were sampled, and the contents of ammonium N (NH⁺⁴ -N), nitrate N (NO^-3 -N), available P (AP) and available K (AK) and related physical-chemical properties, such as mechanical composition, bulk density, water content, and organic matter content were measured, finally, the stoichiometric characteristics of available nutrients were analyzed. [Results] The results indicated that: 1) With erosion intensity increasing, the contents of NO^-3 -N and AP occurred in the collapse mound of strong > moderate > slight, and the content of NH⁺⁴-N was the lowest and AK was the highest in collapse mound under moderate erosion; horizontally, the diminishing order of contents of soil available nutrients were displayed as following: AK > NH⁺⁴-N >NO^-3-N > AP, while the content of each available nutrient decreased vertically as soil depth increasing,and their variance of the same erosion intensity was very little. 2) With different erosion intensities, AN(NH⁺⁴ -N + NO^-3 -N) / AP ratio showed: slight > moderate > strong, and there was significant difference (P < 0.05) between slight and moderate collapse mound; AK/ AN ratio was in moderate >slight > strong, and there was significant difference (P <0.05) between moderate and strong collapse mound; AK/ AP ratio was in slight > strong > moderate, and difference was significant (P < 0.05) between slight and moderate. 3) From upper catchment, collapsing wall, colluvial deposit and channel, the averaged content of NH⁺⁴-N and NO^-3 -N showed a downward tendency, while AP increased gradually, and AK was the lowest at colluvial deposit, but in 3 other sections they varied slightly under different erosion intensities; meanwhile, AN/ AP and AK/ AP ratios decreased from slope of catchment area to channel, but the value of AK/ AN ratio was the highest at channel. 4) Stoichiometric ratios of soil available nutrients were closely correlated to sand, silt, pH value and organic matter, but they were impacted slightly by the clay, bulk density and water content. [Conclusions] collapse mound erosion resulted in variation of soil available nutrients and stoichiometry ratios with different layers and position.