Abstract: The extraction behaviour of gallium(Ⅲ) ion and of metal ions from aqueous hydrochloric acid solution or sulfiric acid and sodium chloride solution with substituted amide-type extractant-dimethylheptyl acetamide (N503) has been investigated systematically.The mechanism of extraction of gallium with dimethylheptyl acetamide was discussed by the maximun saturation method, chemical analysis, infrared spectrum, etc.