Abstract:Based on data of GDP and population from the years of 1998-2009 for the five regions of Sichuan, by employing Variation Coefficient, an analysis is made of the developing trend of the GDP per capita. Then by use of the Theil index and its decomposition formula, some calculation and analysis is done to work out the inter-regional and intra-regional differences. Both of the Theil index and the Variation Coefficient analysis indicate that the overall difference takes an inversed U trend, with a basically even proportion between the inter-regional difference and intra-regional difference；the vigorous driving impetus of Chengdu and other economic cores will eventually even out the regional differences of economic development among the five regions.