Abstract: The species diversity of interlayer plants and their distribution in Dinghushan Biosphere Reserve were studied. The results showed that the species diversity of interlayer plants of Dinghushan was rich. The species diversity of lianas decreased with forest succession while epiphyte showed a contrasting trend. This suggests that the diversity indices of lianas might be employed to measure forest succession. The individual number, species number and Shannon Wiener index of lianas in ravine rain forest and riverbank forest were richer than that of other forests. These indices were the lowest in the most closed forest; monsoon evergreen broad leaved forest . This indicates that both humidity and illumination were important factors affecting the growth and distribution of lianas.