Abstract: Fine roots in the Castanopsis carlesii plantation forest (MZ), the secondary forest of C. carlesii through natural regeneration with anthropogenic promotion (AR), and the secondary forest of C. carlesii through natural regeneration (NR) in Sanming City, Fujian Province, were estimated by soil core method to determine the influence of tree species diversity on biomass, vertical distribution and morphological characteristics of fine roots. The results showed that fine root biomass  for the 0-80 cm soil layer in the MZ, AR and NR  were (182.46±10.81), (242.73±17.85) and (353.11±16.46) g·m^-2, respectively, showing an increased tendency with increasing tree species diversity. In the three forests, fine root biomass was significantly influenced by soil depth, and fine roots at the 0-10 cm soil layer accounted for more than 35% of the total fine root biomass. However, the interaction of stand type and soil depth on fineroot distribution was not significant, indicating no influence of tree species diversity on spatial niche segregation in fine roots. Root surface area density and root length density were the highest in NR and lowest in the MZ. Specific root length was in the order of AR>MZ>NR, while specific root surface area was in the order of NR>MZ>AR. There was no significant interaction of stand type and soil depth on specific root length and specific root surface area. Fine root morphological plasticity at the stand level had no significant response to tree species diversity.