Abstract: The influence of salinity (0‰～50‰) in sand culture on the growth of mangrove species, Sonneratia apetala seedlings was studied. The number of leaves, the length of stem and root, the fresh weight of shoot and root system were inhibited with the increase of salinity. With the increase of salinity, the survival rate of seedlings decreased. The results showed that low salinity (0‰～10‰) promoted the leaf area expansion of S. apetala seedling, while high salinity (15‰～40‰) inhibited it. Content of chlorophyll decreased at lower salt concentration and increased at higher salt concentration. S. apetala seedlings grew normally at low saline habitats when it was lower than 25‰.