The scale of 160 million “three left behind” is huge. The low level of agricultural modernization, the backwardness of rural areas, the widening gap between urban and rural areas, the relatively weak system of national support, agriculture benefit, rural areas, farmers and the low income of farmers are the economic and social foundations of migrant workers, and the reason for the emergence and expansion of the “three left behind”. Agricultural and rural modernization, and peasant professionalization are practical measures to solve the “three left behind” from fountainhead.