Abstract: Progress in studies on salt_resistant mechanism and gene engineering of Dunaliella salina is summed up. The salt_resistant mechanism is very complicated. It can maintain osmotic balance by rapid shrinking or swelling of cells, and then recover their original volume by glycerol synthesis or conversion. Some proteins are also synthesized after hyperosmotic shock. cDNA library and genomic DNA library of Dunliella salina have been constructed. Carbonic anhydrase gene, nitrate reductase gene and several other genes have been cloned. GUS(β_glucuronidase) gene has been successfully introduced in Dunliella salina. Prospects of gene engineering is also given.