The relevance of this study is due to migration processes in Russia, the emergence in Russian schools of migrant children. School practice shows that the education of migrant children the Russian language has its own specifics related to the problems of bilingualism (bilingualism), ethnic identification, insufficient knowledge of the Russian language, weak processes of socialization and adaptation of children-migrants to a different foreign environment. There is a need to develop new approaches in teaching Russian language to children of migrants, the establishment of effective methods and techniques of language teaching. The goal of the article is the study and development of methodical work system on training Russian of children-migrants at elementary school. The leading method to the study of this problem is pedagogical experiment (ascertaining, forming and control stages of experiment), and the method of expert estimations, statistical processing of quantitative results. The main results of the study: the developed system on teaching Russian to children-migrants at elementary school. The proposed system of methodical work of teaching migrants' children Russian language in multi-ethnic primary school classrooms is effective, it provides deep knowledge of younger school students on the Russian language, contributing to the formation of orthographic, lexical and grammatical literacy, speech skills, communicative competences aimed at the development of language personality, socialization of students-migrants. The article can be useful for teachers of higher educational institutions and primary school teachers in the use of the system of methodical work on training of children-migrants of primary school age Russian language in multi-ethnic primary school classrooms.