[Objective] The adaptation strategies of Robinia pseudoacacia seedlings under drought stress were explored, in order to provide support for afforestation site selection of artificial Robinia pseudoacacia forests during vegetation restoration.[Methods]Using the potted water control experiment method, the annual seedlings were used as experimental subjects to study the adaptation mechanism of Robinia pseudoacacia seedlings. Four water gradients were respectively set as follows:75%~90%, 60%~75%, 45%~60%, and 30%~45% of soil water holding capacity.[Results] ① Moderate water stress(45%~60%) and severe water stress(30%~45%) significantly inhibited the growth of seedling, and the plant height, ground diameter and crown width were significantly lower than those of the control group(75%~90%). ② With the deepening of soil water stress, root phosphorus content, specific leaf area and specific root length decreased, while leaf thickness and leaf tissue density increased in Robinia pseudoacacia seedlings. There was no significant different between mild water stress(60%~75%) and the control group, and the growth state of mild water stress was even better than that of the control group at the end of the experiment. ③ Moderate water stress and severe water stress significantly reduced the biomass accumulation of seedlings and increased the root-shoot ratio of seedlings.[Conclusions] Robinia pseudoacacia seedlings adapts to the arid environment by investing a relatively large amount of assimilated material into the defense organization. Severe water stress inhibited the growth of seedlings seriously, while under mild water stress, seedlings could achieve maximum growth benefit.