This paper is  investigated four subject with uses iranian economic data and using the Markov-Switching model during the period (1369: 3-1393: 4), So that: (a) were Examined impact of  the positive and negative Fiscal  shocks on Iran economic growth ( B) the Hypothesis  impact of negative shocks is greater than a positive shock was tested. (C) were tested the impact of government expenditure (fiscal policy multiplier) on economic growth during the recession is greater than the boom period.( d) was determined property of cyclical or counter-cyclical fiscal policy aspects of government spending.The results of Markov switching model revealed that the  impact of positive shocks on growth in boom is positive and the recession is negative   also the  impact of negative shocks on growth in boom is negative and the recession is positive .As well as the Hypothesis  of effects a negative shock is larger than a positive shock in the iranian economy can not be rejected.The nature of government spending in iran economy is cyclical.The remain probability  of  regime one  is 49 percent and The remain probability  of  regime two  is 39 percent.The regime with negative growth (recession) more stable than the boom regime , in Iran's economy.