Allelopathic potentials of the root exudates from peanut (Arachis hypogaea) on rice, maize, radish and rye grass were investigated. The results showed that the root exudates from peanut promoted the seedling growth of tested crops. Further research revealed that the root exudates from peanut were water-soluble materials which contain triacontanol. The promoting effects on crops had difference at different concentrations of the root exudates from peanut.