The dynamics of interethnic relations in conditions of a large city is simulated. The model in the form of ordinary differential equations describes the interaction between ethnic consciousness and its subjects, i.e., the regulation of positive ethnic identities on the basis of social and psychological mechanisms of interethnic comparison and on that of mechanisms of protection of ethnic consciousness. The conditions of stability of equilibria are studied. The bifurcational values of parameters under which stable integration is replaced by ethnocentrism and by intolerance towards other ethnic groups are found. The methods of using the dynamic model in the control of the ethnic situation in multinational cities are discussed.