Little is known about interactions among foundation species and relationships between interactions and tissue nutrients in eutrophic conditions. Therefore, facilitation and competition between Myriophyllum spicatum and Potamogeton maackianus were studied at Kunming City, Yunnan Province (N: 24？44 , E:102？35) in this study. Results showed a shift of interactions between foundation species M. spicatum and P. maackianus from facilitation to neutral to competition with the increase of eutrophication, and species proportion of 1 M. spicatum: 3 P. maackianus had highest biomass and maximal facilitation. Moreover, below ground of P. maackianus had relatively high biomass because of reproductive strategy. Furthermore, M. spicatum and P. maackianus showed relatively high stoichiometric hemostasis. Based on our results, facilitation may enhance the colonization of aquatic plants in freshwater ecosystems threatened by eutrophication, and species proportion of 1 M. spicatum: 3 P. maackianus can be used in restoration of eutrophic lake ecosystems for improving the success of submerged macrophytes restoration.