Salt-tolerant gene, CSRG1, which was isolated from a kind of salt-tolerant mangroves, Avicennia marina, constructed the transgenic plasmid, pGAM189/CSRG1. CSRG1, GUS, Km r and Hyg r could be transferred into tobacco genome by the ameliorated leaf discs method of agrobacterium-mediate transformation. Thirteen stable resistant lines were obtained when fifty transgenic explants were selected through 50 mg/L hygromycin and 150 mg/L kanamycin. Assessments of PCR amplification, Southern blot analysis and GUS histochemical staining showed that CSRG1 has been integrated into the genome of the eleven transgenic lines (frequency of transformation was 22%). Northern bolt analysis revealed that CSRG1 had expressed in transgenic lines. The assessments of salt-tolerant ability and photosynthetic rates indicated that the survival rate of the transgenic lines is 80% 90% and the transgenic lines could increase by 30% 40% in plant height, even when they were cultivated in MS medium containing 2% NaCl and the total seawater (salinity 24). It is supposed that the special physiologic metabolic pathway formed by the products of CSRG1 can really endow the tobacco plants with the high salt-tolerant ability, not only to Na + stress, but also to the comprehensive stress of various ions.Soil salinization is an important factor in confining the development of agriculture. There are about 380 million hectare saline lands all over the world, and one third of irrigated areas are affected by high salinity. 2.17 million hectare tidal flats are along the coasts of China, with 300 hundred hectare increasing each year. There are 37 million hectare saline lands in Chinese inlands, which take about 20% of cultivable areas. Most of crops in the world cannot tolerate high salt stress, and they could not be planted in the tidal flats along the coasts or saline lands. With the increasing of population, decreasing of plantation, and seriously lacking of fresh water, the cultivation of salttolerant crops to sustain the development of agriculture is the first magnitude in the modern biotechnology.In recent years, there are lots of studies on the molecular mechanism of salt tolerance of plants. Many proteins have been found, which include enzymes to synthesize small osmotic molecules, preservative proteins, enzymes relevant to absorbing, transferring and locating salt in the cell, and so on. Now, transgenic plants, which were cultivated by the techniques of gene engineering, can tolerate high salt stress and show a prospective future. Some genes encoding membrane transporter and biosynthesis of the organic salt-tolerant osmotica have been cloned, such as bataine-aldehyde dehydrogenase gene (BADH) [1] , yeast K + /Na + transporter gene [2] , levansucrase gene [3] , 1-phophate mannitol dehydrogenase gene (mtl D) [4,5] , 6-phosphate osmolyte mannitol dehydrogenase gene (gut D) [5] , and so on. These genes have been successfully transferred into tobacco, tomato, wheat, rice, maize, watercress and other crops [1 8] to improve the ability of salt tolerance. The pr...