With the root exudates of two cucumber varieties Jinyan 4 (susceptible variety) and Jinchun 4 (resistant variety) and of black seed squash variety as test materials, this paper studied their effects and action mechanisms on the occurrence of Fusarium wilt on Jinyan 4. The results showed that the occurrence of Fusarium wilt was earlier when treated with the root exudates of Jinyan 4, and the infection rate was significantly higher at 15 days after inoculation, but nearly the same as the control at 20 days after inoculation. On the contrary, the infection rate was significantly lower than the control when treated with the root exudates of Jinchun 4. The plant height and fresh mass of Jinyan 4 treated with its own root exudates were lower than those of the control, and the root vigor decreased but conductance increased. No significant effect was observed in the plant height and fresh mass of Jinyan 4 treated with the root exudates of Jinchun 4 and black seed squash. It could be concluded that the root exudates of susceptible cucumber variety stimulated the growth of Fusarium oxysporum pathogen, while those of resistance cucumber variety and black seed squash were in adverse.