Abstract: In this study, four nitrogen (N) addition treatments, i.e., control (N0, 0 kg·hm⁻²·a⁻¹), low (N1, 60 kg·hm⁻²·a⁻¹), medium (N2, 120 kg·hm^{− 2}·a⁻¹) and high (N3, 240 kg·hm⁻²·a⁻¹) were designed to simulate nitrogen deposition in a subtropical Cunninghamia lanceolata plantation. Changes in soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) contents, stocks and their stoichiometric characteristics were investigated after 10-year-long N addition. The results showed that N addition significantly increased the TN content and stock. Compared to control treatment, TN contents in N1, N2 and N3 increased by 17.31%, 21.59% and 25.01%; TN stocks increased by 22.16%, 31.64% and 39.47%, respectively. N addition had no significant effect on TP contents and stocks. Soil C:N under N addition varied from 8.29 to 14.23, C:P ranged from 54.12 to 95.17 and N:P ranged from 5.16 to 8.91. Stocks of soil C, N and P were significantly correlated with soil stoichiometric characteristics. SOC stocks were positively correlated with C:N and C:P and negatively correlated with N:P; TN stocks were negatively correlated with C:P; TP stocks were negatively correlated with C:P and N:P. Our findings suggest that soil surface carbon, nitrogen and phosphorus stocks are regulated by soil stoichiometric characteristics after long-term N addition, and provide a scientific guidance for the forest management in Cunninghamia lanceolata plantations.