With the continuous development of urbanization process, abundant surplus laborers in China's rural areas transfer to non-agricultural industries, so there are numerous issues in the social security system. Regardless of all sorts of social security systems enacted by the country, migrant workers, who are marginal people of city, have a very low possibility to enjoy social security; thus, it is one of the important problems in the current social development process to deeply think the migrant workers' social security issue. This paper discusses the current situation of the construction of social security system for China's migrant worker group and the migrant workers' major social security risks in our country, analyzes the problems in the construction of social security system for the migrant worker group, and puts forward the countermeasures to further propel the construction of social security system for migrant workers.