Abstract: In order to biological control frequent disease of corn and soybean, the antibacterial activity of several common fungal diseases of corn and soybeans was tested on the in vitro by use of Corydalis chloroform extract. The test result of mycelial growth rates showed that, the inhibition rate of Corydalis chloroform extract on cercosporidium sofinum (Hara) Liu & Guo and Rhizoctonia solani Kuhn reached more 80%, the value of EC50 were 52.98-58.98 mg/L. The test result of spore germination showed that, the inhibition rate of pathogenic fungus were all high, the rate reached 100% on cercosporidium sofinum (Hara) Liu & Guo and Bipolaris maydis. The biological control tested showed that: all of the control effency of disease were below 60% except Rhizoctonia solani Kuhn that reached 61.46%.