The purpose of the current study is to determine the optimum level of the government's debt for the period of the sixth plan period of the economic, social a eviation of the target variables economic growth rate, inflation rate, real GDP and nd cultural development of the government. Therefore, a function of inter periodic loss welfare has been devised for the policy maker in which the squared d consumer price index from the targeted amount in the sixth plan.
To do so, the dynamic optimization was used in which the control amounts including tax revenues, government's current payments, government's acquisition of non-financial assets and liquidity. The result of this study not only determines the optimal level of the public debt, but it also shows tax revenues and optimal liquidity is less than the sixth plan amount and the current payments as well as the optimal acquisition of non-financial assets is more than the approved amount of the economic sixth plan. Also, the optimal economic growth rate is less than 8% in compare with the rate of the Sixth Economic Development Plan that shows the optimal inflation rate for this duration about 13%. Based on the results, it is suggested that policymakers adjust the economic growth rate and inflation rate in their planning