The Gini coefficient is a popular and a widely used index for measuring inequality. But it does not express explicitly a parameter or a value judgment to reflect the opinion of authorities or researches. A generalization of this index known as extended Gini coefficient is introduced to explain different versions of inequality. For decomposing of inequality there are two approaches. First, using a decomposition of Gini coefficient to income components dissent the relative importance of the major income components. Following such decomposition, the marginal impact on inequality due to a change in income or consumption for specific source estimates the Gini income elasticity. The second approach is decomposition of Gini coefficient by subgroups of population. This approach is applicable when the subgroups do not overlap. This article in tends to analyze the structure of distribution of income in Iran by using these approaches.