Aims Enzymes play an important role in the decomposition of soil organic matter. Changes in net primary productivity in response to climate change are likely to affect litter inputs to forest soil. However, the effects of altered litter input on soil enzyme activities remain poorly understood in subtropical forests. Thus, this study is designed to find out if litter manipulation has an effect on enzymes in different subtropical Castanopsis carlessii forest. Methods Three treatments including double litter (DL), no litter (NL) and control (CT) were installed in a secondary C. carlesii forest and a human-assisted naturally regenerated C. carlesii forest, to investigate the responses of 6 soil extracellular enzyme activities. Important findings The activities of Cellobiohydrolase (CBH), beta-1,4-N-acetylglucosaminidase (NAG), Polyphenol oxidase (PhOx) and Peroxidase (PerOx) in the secondary C. carlesii forest were higher than those in the human-assisted naturally regenerated C. carlesii forest, while acid phosphatase (AP) and beta-1,4-glucosidase (betaG) activities had no significant difference between the two forests. Compared to control, both NL and DL treatments decreased the activities of AP, betaG and NAG, but had no effect on the activities of CBH and PerOx, and DL treatment decreased only the activity of PhOx in two forests. Except for NAG activity, the activities of AP, betaG and PerOx decreased more in the human-assisted naturally regenerated C. carlesii forest than in the secondary C. carlesii forest after litter manipulaition. Both Pearson correlation analysis and redundancy analysis showed that soil enzyme activities were significantly correlated with soil moisture content, carbon (C), nitrogen (N), microbial biomass carbon (MBC) and nitrogen (MBN) contents. Therefore, changes in litter input (both increase and decrease) could decrease some major soil enzyme activities such as AP, betaG and NAG in both secondary and human- assisted naturally regenerated C. carlesii forests by decreasing soil moisture content, C and N, MBC and MBN contents. Based on the responses of soil enzyme activity, we conclude that the C and N cycling in secondary C. carlesii forest could be faster compared to that in the human-assisted forest of the same species in the subtropical forest ecosystems.