The contents of eleven mineral elements, including Mg, Fe, K, Ca, Na, Mn, Zn, Cu, Ni, Cd and Cr contents of axenic and natural Dunaliella salina and their culture supernatants in the different period of exponential phase were determined with flame atomic absorption spectrophotometer(AAS). The results show as follows : (1)The contents of Mg, Fe, K, Ca, and Na are between 1 and 10 mg·g-1. The contents of Zn, Cu, Mn, and Ni are between 0.1 and 1 mg·g-1. There are little Cd and Cr in the microalgae. (2) The changes in the content of mineral elements of axenic and natural Dunaliella salina during different phases are almost the same. The contents of Mg, Fe, K, Ca, Na, Mn and Cu decreased along with the growth of the microalgae, especially the content of Ca. The contents of Mg, Fe, K, Ca and Na in the culture supernatants keep stable in the culture process and have no distinct difference among axenic and natural Dunaliella salina. But the contents of Cu and Mn in the culture supernatants increased greatly in the middle and end of exponential phase. (3) The contents of Mg, K, Cu, and Ni show no significant differences in axenic and natural microalgae. The contents of Fe, Ca, Na and Zn in the natural microalgae decreased greatly in the middle of exponential phase and were less than in axenic one, but increased at the end of exponential phase and were higher than in axenic one. These results provide reference for further to applying the resource of Dunaliella salina and studing the relationship of microalgae and associated bacteria in the culture.