In this study, we used pot experiment to explore the effects of different soil pH (4.5, 5.5, 6.5, 7.5, 8.3, 9.5) on the growth, physiological characteristics and active component contents of Polygonum multiflorum Thunb, in order to clarify the effect of soil pH on the growth of P. multiflorum and provide a theoretical basis for selecting suitable planting soil for P. multiflorum. The results showed that: (1) P. multiflorum could grow normally when the soil pH was 6.5-9.5, and the leaves wither and fall off at pH 4.5 and 5.5, and a few cannot survive. The leaf area first increased and then decreased in the range of pH 4.5-9.5, and reached high peaks at pH 6.5 and 7.5, which was significantly higher than that of other treatments. (2) Within the range of soil pH 4.5-9.5, the chlorophyll content, net photosynthetic rate, stomatal conductance and transpiration rate of P. multiflorum showed a trend of first increasing and then decreasing, and peaked at pH 6.5 and 7.5. The contents of proline, soluble sugar and soluble protein in leaves showed a decreasing trend as the pH increased. The content of malondialdehyde in leaves first decreased and then increased with the increase of pH. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) all increased first and then decreased with the increase of pH. (3) Within the soil pH range of 4.5-9.5, the content of active components in the P. multiflorum tubers decreased with the increase of pH, but all reached the standards of the Pharmacopeia of the Peoples Republic of China, and the contents of stilbene glycoside and bound anthraquinone were 1.89% ~ 5.41% and 0.10% ~ 0.25%, respectively. When the soil pH was 4.5, the contents of stilbene glycosides and total anthraquinones in the P. multiflorum were the highest, which were 5.41% and 0.38%, respectively. P. multiflorum had a certain tolerance to acid and alkali, but during the artificial training and planting of P. multiflorum, strong acid soil should be avoided as much as possible. It was advisable to choose neutral to weakly alkaline soil with a pH of 6.5 to 8.3.