[Objective] The impact of soil erosion on nutrient content and stoichiometric ratios in soil is crucial for further comprehending and effective control of quality degradation in the sloping farmlands of black soil regions. [Methods] Selecting straight slopes cultivated for over a century and a convex slope cultivated for more than five decades in the typical black soil area of Keshan County as the research objects, utilizing ¹³⁷Cs tracing method to estimate soil erosion rates on the slopes. Quantitative analysis was conducted on the relationship between soil erosion and key parameters such as soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents, along with the stoichiometric ratio in the ecological chemistry. [Results] (1) Using ¹³⁷Cs tracing technique, the average annual erosion rate of the whole slope was 4 428.56 t/(km²·a), the average erosion rates of the linear and convex slopes were 3 284.53,5 884.59 t/(km²·a), and the total erosion volumes were calculated at 3.21×10⁵,2.94×10⁵ t/km², respectively. (2) The overall carbon/nitrogen ratio (C/N) on the slopes showed a highly significant positive correlation with SOC (p<0.01), and the carbon/phosphorus ratio (C/P) correlated positively and significantly with SOC (p<0.01). Conversely, the nitrogen/phosphorus ratio (N/P) demonstrated a highly significant negative correlation with TP (p<0.01). On linear slopes, SOC, TN, C/N, C/P and N/P were significantly lower than those on convex slopes (p<0.01), while TP content was higher than that on convex slopes (p<0.01). (3) The spatial distribution characteristics of soil erosion on the slopes align with the distribution of SOC, TN and TP. The amount of soil erosion on the slopes exhibited a highly significant negative correlation with SOC, TN, TP and C/P (p<0.01), and a significant negative correlation with C/N (p<0.05). The correlation with N/P is negative, though not statistically significant (p>0.05). [Conclusion] Ultimately, soil erosion redistributed SOC, TN and TP on the slopes, affecting the stoichiometric ratios of soil nutrients and leading to substantial nutrient loss on the slopes.