Abstract: With the process of urbanization accelerating in China, more and more land is expropriated. As a result, large quantities of farmers become landless peasants whose lives are in urgent need for protection. In order to strengthen the social security of landless peasants and further eliminate the disadvantages of the dual urban-rural development, the integrated urban-rural social security system is put forward and into practice. Through the investigation and analysis on the social security of the leading city in the field--Kunshan, we summarized its status of social security, and summed up two shortcomings: on the one hand, there still existed the gap between the rural and urban areas in terms of the household registration system; on the other, the farmers’ self-protection ability was relatively insufficient. Basing on both problems and conforming to the reality of Kunshan, we came up with some corresponding suggestion and measures to promote the construction of the social security system of landless peasants in Kunshan City: increasing financial investment, enhancing supports to social security funds in rural areas, establishing related local regulations, setting up minimum living allowance, mapping out relevant policies to support employment, and promoting employment.