The purpose of this research is to study the effects of environments on the growth of Thalassia hemprichii in cement ponds. The growth index include¡Gchlorophyll concentration, leaf length , hairy root length and their wet weight during experimental periods. Environmental factors use in this study included¡Gsalinity (3 levels), water depths¡]8 levels¡^, sediment types (4 groups) and sun light energy. The results showed that¡G¡]1¡^Salinity significantly affected growth of seagrass, especially hairy root and chlorophyll concentration¡FA negative effect of high salinity on root growth.¡]2¡^ Sediment had no significant effect on seagrass growth, althought a bigger sediment particle, a higher growth rate in root. Analysis of variance from general linear model showed that the sequence of importance to the chlorophyll concentration of leaves are the coefficient of light decline, salinity, time, water depth and cumulated sun light.