The report of the 19th National Congress of the Communist Party of China has expounded the coordinated development strategy,which has provided a new theoretical basis and a new research direction for the theory of state-nation relations. This paper gives a review of four current relations between state and nation,including conflicts,harmony,coexistence and connection in the world,and an incisive analysis of the nature and potential danger of nation-state relations and nation-nation relations. It points out that the theory of nation-state relations in essence advocates a narrow creed of "one nation,one state( country) "in terms of nation-state relations,which would easily bring about extreme national separationism. Multiculturalism is an ideology about the current development of nation-state relations in the modern world. However,we should be vigilant to such ideas as national assimilation,national "melting pot",and national "great platter". As a multiethnic state,China must resume the leading role of "state"in the nation-state relations,and put "state"over "nation"through reflections on the theory of state-nation relations under the new normal situation.