Microbial diversity in decaying maize stalk was characterized by constructing and analyzing rRNA gene clone library. Total 47 OTUs were obtained from 82 bacterial clones, including Proteobacteria (64.6%), Actinobacteria (30.5%), Bacteroidetes (2.4%) and Firmicutes (2.4%). Most proteobacterial clones were members of Rhizobium, Pseudomonas and Stenotrophomonas. Eighty-four percent of Actinobacteria was related to Microbacterium. Only 14 OTUs were identified from 124 fungal clones, including Ascomycota (88%) and Basidiomycota (12%). Sixty percent of Ascomycota were members of Eupenicillium and Paecilomyces but all Basidiomycota were close to Kurtzmanomyces nectairei.