In China, the government had created a policy-friendly educational setting for rural migrant children for a long period after 2001. Yet in 2013, in some metropolitan areas such as Beijing and Shanghai, the schooling policy retuned to more demanding criteria, bringing hardships to many migrant families. This paper examines the power relations underlying the formation of the post-2013 restrictive policy. Utilizing Foucauldian theoretical resources, it develops the work of Bowe, Ball and Gold on policy cycle and produces an updated analytical framework. The findings show that the discursive formation permeating the four coexisting and permeable contexts of the policy trajectory legitimizes the following statements: recruiting migrant children leads to declining educational quality; state school education is a restricted type of social welfare open only to the "contributors to the city"; and standardization is necessary for school enrolment practice. The power relations lie beneath the discursive practices are the exam-orientated education discourse and the disciplinary power of the privileged over the dominated, which objectivize migrants as "outsiders" and a risk to educational quality. This paper demonstrates the analytical capacity of Foucauldian theoretical resources for policy analysis in the Chinese context.