Varieties of pension insurance are considered: joint pension insurance, funded pension insurance, compulsory pension insurance, voluntary pension insurance. The world strategies, models and levels of pension insurance are considered. Each state has chosen its path of building a pension system based on its own demographic and socio-economic characteristics of development. Nevertheless, the main tasks of any pension system are to protect against poverty and to provide a pension that could guarantee a decent standard of living for the pensioner. The analysis of pension insurance and its development in Ukraine and Moldova is carried out. The analysis suggests that joint pension insurance alone cannot cope with the provision of an aging population of countries. The conclusion is drawn on the insufficient development of voluntary funded pension insurance in the studied countries and the need to introduce mandatory funded pension insurance. An author's model of the formation of an optimal pension insurance system is proposed, which describes the problems, their solutions and the purpose of pension insurance.