The relationship between the species diversity of the bamboo mixed stands with conifer, bamboo mixed stands with hardwood and the pure bamboo stands and the disease index of Ceratosphaeria phyllostachydis Zhang in Jiangxi province were investigated and analyzed. The result showed that the bamboo mixed stands with conifer was the most seriously damaged by Ceratosphaeria phyllostachydis Zhang, with disease index 6.321±1.530, while the pure bamboo stands showed the minimum damage, with disease index 4.460±1.903.The species richness index (S), Shannon–Weiner index (H) and Simpson index (D) were the highest in tree layer and shrub layer of bamboo mixed stands with hardwood, while in the pure bamboo stands the plant diversity was the lowest. Diversity in herbage layer of pure bamboo stands was the highest while in bamboo mixed stands with conifer was the lowest. There was a very high significant negative correlation between plant diversity and disease index in tree layer of bamboo mixed stands with hardwood and bamboo mixed stands with conifer, while there was a positive correlation between plant diversity and disease index in tree layer of pure bamboo stands. In shrub layer, D and H in bamboo mixed stands with hardwood and S in pure bamboo stands showed very high significant negative correlation with the disease index; S in bamboo mixed stands with conifer showed significant negative correlation with the disease index. Plant diversity in herbage layer of bamboo mixed stands with hardwood and pure bamboo stands exhibited positive correlation with the disease index while in bamboo mixed stands with conifer exhibited negative correlation.