Abstract: Abstract: To compare allelopathy of different parts of plant Datura Stramonium, the effective components from D. Stramonium root, stem and leaf were extracted with distilled water, and with the treatment with distilled water as CK, the effects of extracted liquid from D. Stramonium root, stem and leaf on seed germination and seedling growth of sesame and millet were studied. The results showed, after treatment by 0.2 g/ml extracted liquid from D. Stramonium leaf, the seed germination rates of sesame and millet were decreased by 83.0% and 83.3% than that of CK respectively, the root and shoot growth of seedling stopped; 0.4 g/ml extracted liquid from D. Stramonium stem decreased the seed germination rates of sesame and millet by 27.6% and 15.8%, root length of sesame and millet seedling by 93.3% and 64.7%, and shoot length of sesame and millet seedling by 51.2% and 18.0% than that of CK respectively. 0.4 g/ml extracted liquid from D. Stramonium root decreased the seed germination of sesame and millet by 31.2% and 56.2%, root length of sesame and millet seedling by 75.1% and 15.0% than that of CK respectively. So the extracts of D. Stramonium leaf had the strong inhibition on the seed germination and seedling growth of sesame and millet, and the extracted liquid from D. Stramonium stem and root also showed lighter inhibiting effects than that from leaf.