Abstract: As a representative lake in Momoge Wetland Reserve, White Crane Lake is facing the risk of salinization and eutrophication.In order to slow down the salinization trend and provide research basis for the restoration of submerged vegetation and survival of species diversity of White Crane Lake, this study investigated physiological indexes of Ceratophyllum demersum in different alkalinity (0, 7, 10 and 17 mmol/L) and mixed saline-alkaline (salinity of 0.3, 0.6, 1, 2 and 4 g/L, corresponding alkalinity of 1.9, 3.8, 6.3, 12.6 and 25.2 mmol/L). The results showed that when the salinity was below 1.5 g/L, alkalinity had no effect on C. demersum. Within the range of the alkalinity gradient set in the experiment, C. demersum grown normally. Although C. demersum peroxidase (POD) and proline showed gradient change, C. demersum was still able to tolerate the alkalinity conditions below 17 mmol/L. With the increase of mixed saline-alkaline concentration, the growth of C. demersum showed a trend from flourish to decline. Under the condition of salinity of 0.6 g/L and alkalinity of 3.8 mmol/L, C. demersum had the best growth with the high-promoting and low-inhibiting ability. With the increase of salinity to 2 g/L and alkalinity to 12.6 mmol/L, C. demersum were under stress and survived partially, and the POD content increased sharply and the difference between plants was large. When salinity increased to 4 g/L and alkalinity reached 25.2 mmol/L, all C. demersum died after 21 days explained by the high concentration of mixed saline-alkaline and the low removal rate of nitrogen and phosphorus that are negatively correlated. This study provides reference for the restoration of submerged vegetation in salinized lakes.