Based on 2008 national comprehensive social survey report, this paper systematically compares and analyzes the status quo of medical insurance of rural migrant workers in different groups, the results show that current public medical expense, basic medical insurance and complementary medical insurance provided by the firms or units for the rural migrant workers are in low proportion, that the number of the rural migrant workers who can use the medical insurance is relatively small, meanwhile, those who have higher technical title or in higher position in the rural migrant worker groups have higher possibility to obtain medical insurance, however, those who work in private enterprises receive smaller medical insurance than those who work in state-owned enterprises or governmental departments. China should make governments play subjective role in accelerating the perfection of basic medical insurance for the rural migrant workers, especially for the weak groups and enhance the enforcement of the medical insurance for the rural migrant workers.