Abstract: In oder to control Phytophthora blight of soyben by new biological pesticides,the bioactivity of Shenqimycin against different stages of Phytophthora sojae was investigated in vitro.The results showed that Shenqinmycin could inhibit mycelia growth,zoospores release and germination with the effective concentration(EC50) values of 2.043 6,230.370 1 and 0.726 5 μg·mL-1 respectively,but have no effect on sporangia production.These findings suggest that Shenqinmycin can obviously inhibit the growth of P.sojae in vitro and have high potential for controlling of Phytophthora blight in soyben.