In order to evaluate the safety of the methanol extracts from Tephrosia purpurea seeds on Crytorrhinus levidipennis adult, the insecticidal toxicity of the extracts were determined against C. levidipennis adult and the third instar nymph of Sogatella furcifera, the surviving period and function response to the third instar nymph of S.furcifera of C. levidipennis adult after exposure to the extracts at the dosage of 10.0 mg/L were studied. The results showed that the insecticidal activity of the extracts against the C. levidipennis adult was lower than that against the third instar nymph of S. furcifera, with respective LC50 value being 298.8 and 16.3 mg/L at 48 h after exposure to the extracts. The function response model belonged to Holling-II type. After exposure to the extracts, the parameters of model changed, in the first day the predatory capacity of the natural enemy was enhanced, and then gradually declined in the second and the third day; the surviving time of the natural enemy after exposure to the extracts was significantly shortened from 21.3 d to 13.3 d. Thus the extract is not safe to C. levidipennis.