Allelopathic effects of vanillin and cinnamic acid, two eggplant autotoxic substances, on pepper seed germination, seedling growth and mycelium growth of Fusarium oxysporum f.sp with different concentrations were studied in laboratory and bioassay experiments by a simulative way. The results showed that both two autotoxic substances exhibited allelopathic promotion at low concentration and allelopathic inhibition at high concentration on pepper seed germination and seedling growth. Allelopathic effect on the peppers and eggplants seed were obviously different. The pepper seeds appeared an apparent lower inhibition comparing to eggplant seeds after treating with two autotoxic substance. All the concentrations (0.1, 0.5, 1, 4mmol/L) of vanillin and cinnamic acid restrained the mycelium growth of Fusarium oxysporum f.sp, and the stimulative rates were enhanced with the increased concentration. Also cinnamic acid at low concentration showed significant allelopathic inhibition to Fusarium oxysporum f.sp.