Peasant-workers have become a social group on scale,who should not be overlooked,and are main force in China's economic construction.Because China's social insurance system lags behind and has defects,the peasant-workers are still at the social border of social insurance.The main content for constructing harmonious society is to perfect social insurance of peasant-workers and to protect the interests of this large-scale group.Based on the status quo of social insurance and self-characteristics of the peasant-workers,this paper gives several ideas about perfecting social insurance system of the peasant-workers.