Pension provision is an essential component of social protection of the population, it is one of the most urgent problems of the state's social policy, and the welfare of Ukrainian citizens depends on the success of the pension system. Therefore, the purpose of the article is to study the system of pension insurance of Ukraine and the prospects for its reformation. To address this goal, the historical-comparative method, systematic and structural analysis have been used. The article deals with the basic principles of pension insurance and the mechanisms of implementation of the three-tier pension insurance system. It is determined that in Ukraine there is a solidarity system of pension insurance based on the principles of solidarity and subsidization and implementation of pension payments and provision of social services at the expense of the Pension Fund. The prospects of transition to a pension insurance system based on the principles of compulsory accumulation of pension funds and financing of expenditures for payment of life insurance pension contracts and one-time payments on conditions and in the manner prescribed by law and non-state pension insurance based on the principles of voluntary participation of citizens, employers and their associations in the formation of pension savings for the purpose of obtaining pension benefits by citizens, which will be complementary to retirement benefits from the first and second levels. The main stages of the formation of pensions in Ukraine are outlined, in particular key changes in the pension legislation and their impact on the pension provision of Ukrainian citizens.