The influence of root exudates on neighboring plants is one of the important factors determining the coexistence status of plants and their neighbors. This study aimed to explore the effects of the root exudates of Stylosanthes guianensis and cultivation substrates on the growth and physiological characteristics of Hevea brasiliensis seedlings. We cultivated H. brasiliensis seedlings with distilled water, sterilized vermiculite, and soil as cultivation substrates, and compared the differences in biomass accumulation and distribution, aboveground and underground morphological characteristics and physiological characteristics of H. brasiliensis when they respectively were irrigated with nutrient solutions containing the root exudates of S. guianensis and containing their own root exudates. The results showed that in soil culture and distilled water culture, the aboveground biomass, underground biomass, total biomass, primary lateral root number, chlorophyll content, carotenoid content, soluble carbohydrate content and root vitality of H. brasiliensis seedlings under the treatment of S. guianensis root exudates were significantly higher than those under the treatment of their own root exudate (P<0.05), except for the difference of root-shoot ratio, plant height and root length. Moreover, except for root vitality, the increase extent of the indexes was distilled water culture > soil culture. The malondialdehyde (MDA) content of S. guianensis root exudate treatment was significantly lower than that of H. brasiliensis root exudate treatment (P<0.05). When cultured with sterilized vermiculite, there were no significant differences in biomass index, morphological index and MDA content of H. brasiliensis seedlings treated with root exudates of two kinds of plants, but chlorophyll content, carotenoid content, soluble sugar content, and root vitality were significantly increased under root exudates of S. guianensis treatment (P<0.05). The comprehensive evaluation of membership function of H. brasiliensis seedlings cultivated in the substrates under the treatment of root exudates of S. guianensis was higher than that of their own root exudates, and the comprehensive evaluation of cultivation substrates under the treatment of the same root exudates was vermiculite culture > distilled water culture > soil culture. It indicates that the root exudates of S. guianensis can significantly improve the physiological function of H. brasiliensis seedlings and promote their growth, but the response of H. brasiliensiss to root exudates is significantly affected by the cultivation substrate.