With Piper nigrum, Mangifera indica and Clausena lansium as the donators, this paper studied their potential allelopathic effects on the germination and growth of Zea mays, Glycine max, Cucurbita moschata, Arachis hypogaea, Raphanus sativus, Echinochloa crusgalli, Digitaria sanguinalis and Stylosanthes guianensis. The results showed that the aqueous extracts of these donators could inhibit the germination and growth of Z. mays, G. max, C. moschata, E. crus-galli and D. sanguinalis at high concentration, but stimulate them at low concentration. In rhizosphere soil of P. nigrum and M. indica, the germination and growth of Z. mays L was stimulated, while A. hypogaea was inhibited. The aqueous extracts of the donators were extracted by ethyl acetate and n-butanol, respectively, and the inhibitory activity of both aqueous and n-butanol fractions from P. nigrum and M. indica on Z. mays, R. sativus and S. guianensis was stronger than that of ethyl acetate fraction, indicating that P. nigrum and M. indica contained the allelochemicals with high polarity.