Abstract: A kind of marine bacteria chromogenic medium was improved to enhance effect of detection by changing the CHROMagar marine bacteria sodium thiosulfate in the culture medium (0.500; 0.375; 0.250; 0.125g/L), ONPG (1.5; 1.0; 0.5g/L), fiber two sugar (4.00; 3.0; 2.0; 1.0g/L) concentration. The results showed that there were more marine bacteria?colony numbers and more clear colony color when Sodium thiosulfate reached to 0.25g/L, Fiber two?sugar reached to 2.0g/L and ONPG reached to 0.5~1.0 g/L. It indicated that this research could reduce the cost, furthermore, it also could improve the detect effect.