At a time when the world is affected with lot of changes, shaking the financial and economic crisis, large-scale apocalypse, wars, unemployment and hunger that force the entire group of nations into migration, changing the entire structure of the population in the world and in our country. The structure of the population is divided into five indicators: biological structure, breakdown by age and gender, ethnic composition, religious structure, economic structure and educational structure by level of education. The number and composition of the population according to various demographic and socioeconomic characteristics which has the fundamental deteminants on the present and future social, economic and demographic development of Croatian. Prediction of future demographic change is very important in areas of low fertility, such as Croatia, where the current number of children born is insufficient for recovery of the population. Population aging is becoming a major challenge of social policy, where immigration has a limited impact on slowing the aging population and demographic growth, in which the system measures of the community should be quite comprehensive with respect to all spheres of human life where demographic changes has greatly influence. In this final paper is analysed the structure of the population in Croatia, the projection of population migration, the question is it migration trend or need and it is presented the projection of the population by 2031 year.