The effects of light intensity on seeds germination, seedlings growth and physiology of Ottelia acuminata were studied through simulated experiments in order to explore the reasons for the disappearance of the plant in Lake Dianchi in China and the possibilities of its restoration. The results showed that light intensity had no significant effect on the seeds germination, while the influences of different light intensities on the seedlings growth of O. acuminata were significant. The blades length, blades width and plants height under shading rates of 71.8% and 91.5% were all significantly higher than those under 0% and 97.6% shading rates, and the biomass under that two shading rates were also obviously higher than those under 97.6% shading rate. Our results also showed that light intensity had prominent influence on chlorophyll-a content in the middle period of this research, but no remarkable effects were found in the effect of light intensity on peroxidase activities in the leaves. Chlorophyll-a contents in the leaves under shading rate of 71.8% were significantly higher than those under 0% and 97.6% shading rates. Although low water transparency and weak light intensity caused by eutrophication did not influence the seeds germination of O. acuminata, they affected the seedlings growth and physiological characteristics, which may impact the reproduction of the plant eventually. Therefore, it is necessary to increase the water transparency and improve the light condition in order to restore O. acuminata in Lake Dianchi.