【Objective】To analyze peanut root exudates and study the allelopathic effects of peanut root exudates. 【Method】Compounds extracted from peanut root exudates were identified by GC-MS technique. The allelopathic effects of peanut root exudates on the peanut seeding growth were analyzed using biological test at the concentrations of 0,1×10^-5,1×10^-4 and 1×10^-3 mol·L^-1.【Result and conclusion】The peanut root exudates included organic acid, alcohol, ester, ketone, aldehyde, benzene, hydrocarbon and so on. Benzaldehyde and 4-ethylbenzoic acid, which showed an allelopathic effect on peanut, were found to be the major components of peanut root exudates. 1×10^-5mol·L^-1 Benzaldehyde，4-ethylbenzoic acid and ferulic acid promoted or weakly inhibited peanut seeding stem length, root length, dry mass of root and shoot. Compared with the control, 1×10^-3 and 1×10^-4 mol·L^-1 benzaldehyde,4-ethylbenzoic acid and ferulic acid significantly inhibited peanut seedling growth (P<0.05).The SOD activity, POD activity and MDA content of two peanut varieties leaf showed a rising trend to varying degrees at different concentration levels of benzaldehyde, 4-ethylbenzoic acid and ferulic acid，and there was significant difference between the high concentration treatment (1×10^-3 mol·L^-1)and the control (P<0.05). In conclusion, there are allelophathic substances in peanut root exudates, which is one of the main factors of continuous cropping barrier of peanut.