We investigated the effect of simulated sea level rising on the main osmolytes of Hibiscus hamabo Sieb.et Zucc,such as soluble protein,soluble sugar and starch.The results showed that both soluble protein and soluble sugar tended to increase first but decrease later with the prolonged time of flooding,and their changes were similar.The starch increased first and then decreased,while it increased again,showing a curve similar with "N".Through the comparison and analysis of every treatment, we found that H.hamabo Sieb.et Zucc still had stronger resistance in the level of osmolytes under the flooding condition of 45 cm·d^-1 and 6 h·d^-1.The study indicated that under slight flooding stress condition there was a positive correlation between the contents of soluble protein and soluble sugar,and a native correlation between the contents of soluble sugar and starch.It showed that the main osmolytes of H.hamabo Sieb.et Zucc were synergetic under certain extend flooding condition,and the soluble sugar might transform to the starch.