The famous economist Amartya Sen pay a lifetime attention to the fate of the vulnerable groups.His ideas of economic development fully reflects his concern and sympathy for the bottom of the victims and “fell on the last” farmers.This article discusses the outstanding performance of Sens’ development economic ideas from three aspects.Firstly,he criticizes the modern western mainstream economics ignore social vulnerable groups.Secondly,he criticizes the theory of dual economic structure of farmers' poverty represented by Lewis.Thirdly,he contends that the development of farmers should be treated with freedom.The article thinks that Sen's development economic ideas have important theoretical and practical significance to china’s promotion of the development of “three rural”,especially to the strategy that the newly proposed “content-oriented new rural ” and “people-oriented new rural ” should be developed concertedly.