Abstract: Dunaliella salina Mitogen-activated protein kinase gene (GenBank Accession No. JQ782412)（named DsMAPK）was cloned by RT-PCR and RACE technology for further bioinformatics analysis. The result shows that the full length of cDNA for DsMAPK is 1861bp, which contains 67 bp 5′UTR, 387bp 3′UTR and 1407bp open reading frame, coding 468 amino acids. The protein is a hydrophilic protein without signal peptide. According to our analysis, the protein belongs to a non-transmembrane protein category and is located in cytoplasm. Secondary structure prediction indicates that the protein consists of 25.2% a-helix, 12.4% strands and 62.4% random coils. Protein Drthology shows that the protein has a closest genetic relationship with those of Chlamydomonas reinhardtii and Volvox carteri f. nagariensis. By using real-time quantitative PCR ,we monitored the expression value of DsMAPK .The results show that the expression level of DsMAPK mRNA has significantly risen under high salt stress(including 3 mol/L NaCl), and it achieved the highest level after 1h dispose of 3 mol/L NaCl, which is 5 times larger than that of under 1.5 mol/L NaCl untreated condition(P<0.01). The research laid a foundation for further study of the function and working mechanism of DsMAPK.