With the increasing trend of population aging, the pressure of pension payment increases year by year, and the reform of basic oldage insurance system is imminent. The reform of the system led to the decrease of the replacement rate of the old-age insurance of the employees, and the development of the supplementary old-age insurance system played an important role in raising the total replacement rate of the old-age insurance. Based on the actuarial model of supplemental pension insurance replacement rate, this paper calculates the replacement rate of basic oldage insurance and occupational pension, enterprise annuity replacement rate, compares the change of old-age insurance system after the reform of old-age insurance system to compare the impact of enterprise annuity on the replacement rate of enterprise employees' pension insurance to promote enterprises to establish enter-prise annuity for employees.