Based on the perspective of household system and combined with the research materials of household system,this paper sorted out the historical track of the change in smallholders’grain-growing motivation,and revealed the internal mechanism of the decline of smallholders...MORE Based on the perspective of household system and combined with the research materials of household system,this paper sorted out the historical track of the change in smallholders’grain-growing motivation,and revealed the internal mechanism of the decline of smallholders...