In order to study the changes of nitrogen and phosphorus stoichiometry in soil and runoff under long-term fertilization and tillage, five treatments (three replicates were set in each treatment) were set up on the sloping land of purple soil∶ downslope tillage without fertilization (CK), downslope tillage with mixed application of chemical fertilizer and organic fertilizer (T1), downslope tillage with chemical fertilizer (T2), downslope tillage with 1.5 times increment of chemical fertilizer (T3), and contour tillage with fertilizer (T4), to analyze the change characteristics of soil total nitrogen (TN_S), soil total phosphorus (TP_S) and TN_S∶TP_S, runoff total nitrogen (TN_W), runoff total phosphorus (TP_W) and TN_W∶TP_W in 83 runoff-producing events during 2008-2017. The results showed that the contents of TN_S and TP_S in CK treatment were not significantly different from those in T1 treatment, but significantly lower than those in T2, T3 and T4 treatment. The main reason was that the application of chemical fertilizer significantly increased the content of nitrogen and phosphorus in soil. The mean value of TN_S∶TP_S was 3.55~4.79, and the CV value was 0.39~0.94, indicating that fertilization had no significant effect on N/P ratio. The concentration of TN_W in CK treatment was significantly higher than that in other fertilization treatments, and the concentration of TN_W in T1 treatment was not significantly different from that in T2 treatment, but significantly higher than that in T3 and T4 treatment. The TP_W concentration of CK treatment was not significantly different from that in T2, T3, T4 treatment, but significantly lower than that in T1 treatment. The TN_W∶TP_W of CK treatment was significantly higher than that in fertilization treatments, but there was no significant difference in TN_W∶TP_W among fertilization treatments. The mean values of each treatment was 25.48~56.83, and the CV value was 1.11~1.80. Fertilization significantly reduced the N/P ratio in runoff and stabilized the difference between rainfall events. Annual mean TN_W and TP_W were both significantly positively correlated with annual mean TN_S and TN_S∶TP_S, indicating runoff N loss concentration was significantly affected by soil N content, while annual mean TN_S∶TP_S and TN_W∶TP_W were not significantly correlated. Fertilization and tillage could decouple the relationship between nitrogen and phosphorus stoichiometry in soil and runoff. The results can provide theoretical basis for the prevention and control of agricultural non-point source pollution.