In this study, we used the PEG-6000 to simulate drought stress, and determined the content of soluble sugars, soluble protein, MDA(Malondialdehyde), and free proline, and changes in enzyme activities of SOD(Superoxide dismutase) and POD(Peroxidase) in roots of Amorpha fruticosa seedlings and in their anatomical features. Our objectives were to examine the effects of different levels of drought on the physiological indices and internal anatomical structures of seedlings of Amorpha fruticosa. Furthermore, we explored the adaptability response and regulation mechanism to water stress of Amorpha fruticosa seedlings. The results indicated that MDA appeared when the concentration of PEG-6000 was more than 50g/L, and the membrane system of Amorpha fruticosa seedling roots began to suffer damage. When the PEG-6000 concentration reached 250g/L, the extent of damage was significantly enhanced, reaching 1.6 times that of the the control group, and at the beginning of osmotic adjustment (free proline content increased significantly), it reached 3.8 times that of the control group. When the concentration of PEG-6000 solution was less than 200g/L, the osmotic adjustment process was not initiated in the roots of Amorpha fruticosa seedlings with free proline. The physiological metabolism of the cell was verified through changes in soluble sugar and soluble proteincontent, and SOD and POD activity. When the concentration of PEG-6000 was 200g/L, the soluble sugar content was 0.121mg/g, reached its lowest point, and then increased. As the PEG-6000 solution concentration further increased to 250g/L, the soluble sugar content in the roots of Amorpha fruticosa seedlings rapidly increased to 0.64mg/g, which was 63.37% of that of the control group. Soluble protein content in the low concentration of PEG-6000 solution (50g/L) treatment decreased to 61.5% of that of the control group, followed by fluctuating changes. SOD and POD activities were similar to PEG-6000 simulated drought stress, and rapidly responded to PEG-6000 simulated drought stress treatment. Simultaneously, the enzyme activity of POD and SOD were increased. When the concentration of PEG-6000 was 50g/L to 100g/L, the synthesis of antioxidant enzyme was the highest, and then it decreased. SOD amplitude activity differed by more than six fold. Changes in POD activity were relatively small, and the difference in amplitude was less than a multiple of one. The 60-、day PEG-6000 solution simulating the drought stress affected the growth and development of the root system of the Amorpha fruticosa seedlings. With the increasing concentration of PEG-6000, the diameter of the vascular bundles increased. At the same time, the diameter of the catheter decreased, but its density increased. When the concentration of PEG-6000 reached 250g/L, the catheter density increased by 41.3% compared with that of the control group, and xylem thickness increased by 91.5% compared with that of the control group. The results showed that under different levels of drought stress treatments, the internal physiology and root anatomical structures of Amorpha fruticosa varied. The stress conditions of water and self-、growth and development balance needs were satisfied by altering their physiological metabolism and the internal anatomical structure of the roots.