Abstract: By the methods of spacetime substitution and PVC tube closedtop in situ incubation, this paper studied the soil mineralizedN content, N mineralization rate, and N uptake rate in Phyllostachys edulisbroadleaf mixed forest (PBMF) formed by P. edulis expansion and its adjacent evergreen broadleaf forest (EBF) in Dagangshan Mountain of Jiangxi Province, China. There existed the same spatiotemporal variation trend of soil total mineralizedN (TMN) content between the two forests. The annual average N mineralization rate was slightly lower in PBMF than in EBF. In PBMF, soil N mineralization was dominated by ammonification; while in EBF, soil ammonification and nitrification were wellmatched in rate, and soil nitrification was dominated in growth season (from April to October). The N uptake by the plants in PBMF and EBF in a year was mainly in the form of NH₄⁺-N, but that in EBF in growth season was mainly in the form of NO₃^--N. These findings indicated that the expansion of P. edulis into EBF could promote the ammonification of soil N, weakened soil nitrification and total N mineralization, and also, increased the NH₄⁺-N uptake but decreased the NO₃^--N and TMN uptake by the plants.