Based on the clear introduction of the connotation of marginalization, the index of diagnosing the marginalization degree is put forward. According to the 685 copies of questionnaires on peasant households in Tongcheng County of Hubei Province and the statistical data of local government, marginalization of arable land and its correlation with rural labor migration in Tongcheng County are studied by using aggregative indicator method, clustering analysis method and correlation analysis method. Result shows that marginalization of arable land has happened two times in Tongcheng County since 1985. Dry land has severer marginalization degree than paddy field. There is significant correlation between marginalization degree of arable land and rural labor migration; and the correlation between marginalization degree and rural labor migration in paddy field is greater than that in dry land. Marginalization of arable land will advance the rural labor migration, while in response to the poor current circulation of lands; the rural labor migration will further deepen the marginalization degree. Marginalization of arable land is one of the important factors affecting the labor migration in rural areas.