Abstract: Led by bioassay, the insecticidal activity, heat stability, public safety and dissolubility of metabolites produced by isolated Paecilomyces fumosoroseus sw 03085 and then cultured in SDB liquid medium were studied.It was indicated by the results that the metabolites produced by purified sw 03085 were poisonous to tobacco aphides and other pests, but safe to crop plants.The active substances were compounds with intermediate polarity that could be fully dissolved in methanol, acetone, and ethyl acetate, and partially dissolved in chloroform.Temperature had little impact on the stability of the active substance.The toxicity of the active substances was high to Myzus persicae and Bemisia tabaci and the mortality of these pests could reach about 100%within 24 hours, but the toxicity of the metabolites was low to other pests(Tomicus sp, Anomala sp.Pieris sp.et al.)experimented, which indicated that the active substances from isolated Paecilomyces fumosoroseus sw 03085 were selective to different pests.