To explore the effect of legal system to the development of agriculture,the methods of history studies,case analysis and comparative jurisprudence are devoted to explain the phenomenon of Sunkist.The U.S.legal system supporting the citrus industry at all stages has been embodied in the industry,organization,agricultural products,merchandise,brand and so on.With the actual situation of China's agricultural,the American experience could be referred to expedite the promotion and improvement of the legal system of modern agriculture overall from the abovementioned aspects.