Abstract: The paper deals with seed collection period, seed sowing, seedling nursing techniques, seedling growth rhythm and essential environmental factors on Sonneratia carseolaris.The results have shown that July to August are the best period for the seed collection in Dongzhai Harbor of Hainan Province.Both sea mud and nutritive soil can be used for sowing bed, but the latter seedling height was 26.8% higher than that of the former before transplanting.The best container substrate is the mixed nutritive soil, on which, the seedlings grow very well and the seedling certified rate can reach to 98.4% when lifted from nursery, the sea mud that is short of phosphorus is the second, and the red soil that is short of nutriment is the third.The anaphase growth has evidently presented in the annual growth period of seedling height and basal diameter, and the growth rhythm can be analyzed by the equation Y(t)=1/(a+be-t).It has been revealed by using grey relation analysis method that the sea water saltness and rainfall are the essential environmental factors affecting the seedling growth.