Abstract:The hypotheses that soil microbial taxonomic diversity responds with different vegetations and seasons, four successional communities: Tussock (T), shrub (S), secondary forest (SF) and primary forest (PF), were tested in Huanjiang county, southwest China. The total soil microbial DNA was extracted, following the amplification of bacterial 16S and fungal 18S rDNA, and get fingerprinting by denaturing gradient gel electrophoresis (DGGE) in order to determine for these communities. In reverse with the soil bacterial communities, the soil fungal ones presented obviously dominant phylotypes but no continuity along successional ongoing. Significant effects of vegetation on soil microbial diversity measured by Shannon index (p<0.05, p<0.001, respectively), but no prominent trends along successional process, were examined. Bacterial and fungal diversity also significantly affected by seasonal exchanges (p<0.001, p<0.001, respectively), further more, these shifts (p<0.01) of diversity in T soil other than in SF and PF soils were observed. Meanwhile, there exist some interaction effects between the vegetation and the season. Significant seasonal shifts (p<001) in microbial taxonomic diversity in T soil, but not SF and PF soils were detected. Significant positive correlations were found between bacterial and fungal taxonomic diversities. Soil microbial taxonomic diversity gets steadier along vegetation succession and, in early restoration stage of degradation ecosystem in karst area, large but unstable microbial diversity exists in soils.