The measurement of regional economic disparities is a scientific issue, closely related with scale. Based on Geographical information system (GIS) technology, selecting Lorenz curve, GINI coefficient and THEIL coefficient as the measuring index, this paper discusses the spatial scaling effect using grid method by up scaling. The main findings are as follows: With the increase of spatial grain in size, GINI coefficient and THEIL coefficient both present a decreasing tendency and the degree of downward bending of Lorenz curve is also decreasing, which all show regional economic disparities decrease. With the first 3–7 increase of spatial extent, GINI coefficient and THEIL coefficient change greatly and they are no obvious regularity. Since then, the measuring results tend to stabilization with the increase of spatial extent. On the large scale, the whole spatial rule is easy to find, but the details on the small scale are omitted. Meanwhile, on the small scale, the micro rules are easy to find, but the macro rule cannot be presented. Therefore, the suitable scale in the study of regional economic disparities can be determined by the specific research purpose and research object.