T he effects of culture time , concentration of N aCl , CaCl2 , M gSO4 and pH v alue in medium on the growth and exo polysaccharide contents of Aphanothece halophytica Fremy were determined .The results showed that the alga produced a large amount of exopoly saccharide during the late logarithmic phase .NaCl levels had evident effect on the growth and exopolysaccharide contents.CaCl2 , M gSO4 levels and pH v alue in medium had effects in different degrees.W hen concentration of NaCl, CaCl2 and M gSO 4·7H2O in medium w ere 1 ～ 1.5 M , 0.5 g/l , and 5 g/ l respectively , the exopolysaccharide content was twice as much as that produced in the basic medium during the late logarithmic phase .