A long-term field experiment of nitrogen (N) and phosphorus (P) additions was established in Chinese fir plantations in subtropical China. Four treatments, i.e. control (CK), N (50kg N hm^-2 a^-1), P (50kg P hm^-2 a^-1), and NP (50kg N hm^-2 a^-1+ 50kg P hm^-2 a^-1),were selected in this study. We studied the effects of N and P additions on the soil mineralization rate of carbon (C_min) and nitrogen (N_min) and the kinetics of β-glucosidase(βG)and N-acetyl-glucosaminidase(NAG). The results showed that (1) N additions had negative effects on C_min and N_min, which were lower by 25% and 18%, respectively, compared to CK. (2) P (P, NP) additions decreased the V_max and K_m of NAG by 26%-60% compared to CK, whereas NP combined additions greatly enhanced the catalytic efficiency (V_max/K_m) of βG and NAG (P<0.05). (3) C_min was positively correlated with dissolved organic carbon (DOC) contents, whereasN_min was positively correlated with pH and negatively correlated with NH₄⁺-N and NO₃^--N contents. The catalytic efficiencies of βG and NAG were negatively correlated with NH₄⁺-N and NO₃^--N contents (P<0.05). The K_m of βG and NAG was positively correlated with NH₄⁺-N and NO₃^--N (P<0.05), The V_max of βG was positively correlated with NH₄⁺-N and NO₃^--N (P<0.05), and the V_max of NAG was negatively correlated with soil organic carbon, total nitrogen, total phosphorus, and available contents (P<0.05). Our results suggest that N additions had negative effects on C_min and N_min by decreasing soil pH, increasing soil available N contents, and inhibiting the V_max/K_m of βG and NAG, whereas NP additions increased soil available P and the V_max/K_m of βG and NAG in southern subtropical Chinese fir plantations.