Slash and burn is a traditional and efficient way of removing forest harvest residues in south China. This study was conducted to investigate the effects of fire-derived black carbon on soil labile carbon and nitrogen pools in a Pinus massoniana Lamb. plantation in subtropical China. Three levels of black carbon[nil (B0), single (B1), and double rates (B2)] were used by transferring black carbon across the plots after slash burning. The unburnt area (UB) adjacent to the burnt site was selected as the reference site. Soil dissolved organic C (DOC) and N (DON), inorganic N, microbial biomass C (MBC), and N (MBN) contents were measured 1 year after the black carbon application. The results showed that the effects of fire on the soil DOC and DON differed among the sampling depths, and no significant differences in soil DOC and DON contents between the burnt and reference soil were observed at the 0-10 cm depth, whereas the DOC and DON contents in 10-20 cm soil layers were significantly lower at the burnt site than they were at the reference site (P < 0.05). The soil inorganic N, MBC, and MBN contents were lower at the burnt site than those at the reference site were, although the differences were not statistically significant (P > 0.05). Soil moisture content, pH, total C, total N, ammonium, and soil MBN content increased with the amount of black carbon input. Especially, the soil ammonium content under the B2 treatment was significantly higher than those under B0 and B1 treatments were at the 10-20 cm depth (P < 0.05). Moreover, the removal of black carbon significantly decreased the soil MBN content compared to that of the reference site. In conclusion, this study suggested that the black carbon input played a key role in the recovery of soil microbial communities and N retention after slash burning, and the underlying mechanisms by which black carbon regulates soil N cycling should be investigated in future studies.