In the context of the aging population, the debt risk and solvency situation of China’s pension plan are of major concern for government and individuals. The aim of this paper is to project public pension liabilities and evaluate the solvency sustainability of China’s pension reform during transition periods. By using cohort component and actuarial models, transition debt and solvency sustainability are projected under the existing policy scenario and several sets of hypothetical policy scenarios. We find that the transition liabilities will peak in 2035 and the pension plan will become unsustainable in 2048 under existing policies. In the proposed scenario, postponing retirement age helps to maintain pension plan sustainability until 2083, but this option can’t solve the financial distress in the long run. Further, the transition pension debt will double in the peak moment if the retirement age is postponed for five years, which would pose a risk to the liquidity of the fund. Moreover, an increase to invest return can only improve the baseline solvency in short term. Sustainable options should be designed as composite reform measures, including retirement and investment adjustment.