Fiscal decentralization that is considered a transfer of responsibilities that associated with accountability to sub – national governments, increases efficiency and providing better access to public goods in the Economy. According to the five-year development plans of Iran creating and allocating structure for provincial budgeting, fiscal decentralization generally is moving in the costs of its Provinces in order to give more responsibility to the provincial development projects. The aim of this study is an investigation of effect for partial fiscal decentralization on regional economic growth of Iran. Fiscal decentralization index is proportion of provincial's capital assets to government's capital assets, So this researches the effects of decentralization on economic growth in the framework of Solow's growth model. That the results based on data from 30 provinces between 2000 and 2007 on the panel data estimation, shows partial fiscal decentralization which has a non-linear relationship with the growth (convex shape) and partial fiscal decentralization Indicts the Optimal degree in growth of regional economy in Iran.