Regarding the high importance of gross domestic product (GDP) and identifying the fluctuations and variables affecting it, this research studies factors influencing Iran GDP according to one of the newest economic models, IS-MP-AS (Romer, 2000). Beside the estimation of this model, the effect of IS-LM-AS on Iran’s economy is also examined and results are compared with Romer’s model. Research results show that Iran GDP, in the framework of IS-MP-AS, has a negativecorrelation with budget deficit, predicted inflation, coin prices (to show the effect of wealth) and a positive correlation with real effective exchange rate and oil revenues. It can be well defined by these five variables. According to IS-LM-AS, there is also a positive significant correlation between money supply and GDP. Other estimations reveal no significant difference between two models.