The article analyzes the ethno-demographic policy of the CPSU – CPU of the 60’s – 70’s of the twentieth century, which was guided by the priority of national unity of the entire Soviet people and neglected the value of the Ukrainian ethnic group and its national development. The state command-administrative system under the slogans of “proletarian internationalism”, “prosperity and rapprochement of nations in the USSR”, “formation of a new historical community – the Soviet people” pursued a policy of assimilation of the titular nation of the Ukrainian SSR. Demographic, economic and social processes that took place in the society of that time, especially decreased in some regions of the republic the number of indigenous peoples. The correlation of macro-processes (intra-republican and inter-republican migration) with internal micro-processes in Ukraine (enhanced russification, interethnic marriages, etc.) promoted assimilation, depopulation of Ukrainians and threatened their national future. The paper finds that in the conflict of unfavorable circumstances resulting from the Soviet assimilation policy, the number of the Ukrainian nation in the USSR slowed down, difficult, but did not grow in both quantitative and qualitative terms.