Abstract:The leaf anatomical changes of Bruguiera gymnorrhiza seedling under gradient salinities were observed, and the effects of salt stress on plant growth were analysed. The hypocotyl of B. gymnorrhiza could germinated under the salinities from 0‰ to 50‰. However, the plant height, fresh weight and leaf area had negative correlation with salinities. With increment of salinity, the thickness of upper and lower cuticle, upper and lower epidermis, and the densities of tannin cell increased, but the thickness of upper and lower endodermis, the intercellular spaces of spongy tissue of leaves decreased. The thickness of palisade tissue decreased, and that of spongy tissue had no relation with salinity, the ratio of the thickness of palisade tissue to spongy tissue decreased with increasing salinity. With increasing of salinity, there were no obvious difference in quantity and shape of chloroplast under SEM, but their location in palisade cells occurred change. All these changes made seedlings photosynthesis inhibited and growth stunted.