Abstract: A strain BZ-1 with simultaneous hydrogen production and nitrogen fixation ability was screened from paddy soil in South China by anaerobic microbial enrichment and Hungate tube rolling techniques. The strain was identified as Clostridium sp. by morphological observation and phylogenetic analysis based on 16S rRNA gene sequence. The hydrogen production capacity and the synergistic nitrogen fixation hydrogen production capacity of strain BZ-1 was determined by monitoring hydrogen production, nitrogenase activity, fermentation products and biomass. The results showed that the main products of glucose fermentation by strain BZ-1 were butyric acid, acetic acid and lactic acid. Strain BZ-1 had nitrogenase and was able to grow with N₂ as the sole nitrogen source. Strain BZ-1 had the ability of synergistic nitrogen fixation and produce hydrogen, and the hydrogen production of strain BZ-1 under nitrogen fixation condition was higher than that under non-nitrogen fixation condition. The acquisition of strain BZ-1 will provide a new method for improving soil fertility and alleviating heavy metal stress in crops.