We investigated the allelopathy effects of root exudates benzoic acid; 1,2-benzenedicarboxylic acid bis(2-methylpropyl) ester; hexadecanoic acid; and 2,2-bis(4-hydroxyphenyl) propane of ginseng (Panax ginseng) at different concentrations on the colony growth and conidia germination rates of Rhizoctonia solani, Alternaria panax, Phytophthora cactorum, Sclerotinia schinseng, Cylindrocarpon destructans, and Trichoderma viride of ginseng. The results showed a significant variation in the allelopathy effects of root exudates on pathogens and Trichoderma viride. Benzoic acid at concentrations that correlated negatively with the colony growths of Rhizoctonia solani, Sclerotinia schinseng, and Cylindrocarpon destructans and the conidia germination rates of Alternaria panax and Cylindrocarpon destructans correlated positively with the colony growths of Alternaria panax and Trichoderma viride. It inhibited the colony growth of Phytophthora cactorum at low and high concentrations and accelerated the growth at a medium concentration. 1,2-Benzenedicarboxylic acid bis(2-methylpropyl) ester at concentrations that correlated negatively with the colony growth of Rhizoctonia solani, Alternaria panax, Sclerotinia schinseng, and Trichoderma viride, inhibited the colony growth and the conidia germination rate of Cylindrocarpon destructans at low and high concentrations and accelerated them at a medium concentration. It inhibited the colony growth of Phytophthora cactorum at low and medium concentrations and accelerated it at a high concentration. Concentrations of 2,2-bis (4-Hydroxyphenyl) propane that correlated negatively with the colony growths of Rhizoctonia solani, Alternaria panax, Phytophthora cactorum, and Trichoderma viride and with the conidia germination rates of Alternaria panax and Cylindrocarpon destructans, inhibited the colony growths of Sclerotinia schinseng and Cylindrocarpon destructans at a high concentration and accelerated the growths at a medium concentration. Concentrations of hexadecanoic acid that correlated positively with the colony growth of Cylindrocarpon destructans, Phytophthora cactorum and Trichoderma viride correlated negatively with conidia germination rate of Cylindrocarpon destructans and inhibited the conidia germination of Alternaria panax at a medium concentration. Also we found that, mixture that mixed with four root exudates equally at concentrations correlated negatively with the colony growth of pathogens and antagonistic Trichoderma strain of ginseng.