Abstract: There has been increasing effort in the research and development of biological herbicides because of their low toxicity. Myrothecium roridum, strain BC-1 was isolated from diseased Echinochloa crusgalli leaves in order to obtain a low toxicity and effective biological herbicide. The BC-1 strain was identified using its culture characters and 16S rDNA sequence analysis. The optimal mycelium growth media were PDA and PSA medium. The optimal culture temperature is 25-28 ℃, and optimal initial pH of culture media was 6-7. Darkness was beneficial for mycelium growth. The optimal mycelium growth carbon source is maltose, and the best nitrogen source was NH₄NO₃. Additionally, biocontrol testing showed that the E. crusgalli were all infested with BC-1 21 days after innoculation, and fresh weight inhibition was 93.7%. However, the fresh weight inhibition effects of BC-1 on Digitaria sanguinalis, Setaria viridis, Descuminia sophia and Amaranthus retroflexus were only 33.7%, 28.3%, -3.2% and 16.8% respectively. Crop safety analysis showed that the strain BC-1 was safe to Zea mays, Triticum aestivum and Oryza sativa. This study suggests that strain BC-1 has potential to be developed into an effective microbial herbicide with economic and social benefits.