The version 7 and version 8 of TOMS (Total Ozone Mapping Spectrometer) ozone data sets are most widely used at present. The TOMS data of version 7 and version 8 are compared and the features and distribution of the differences between the data of version 7 and version 8 are discussed. By means of the two version ozone data of TOMS from November 1978 to December 2001, the spatialte mporal variation of the differences between two version ozone data are analyzed in detail. Results show that though quite good relationship exists between two versions data sets, there are significant spatialtemporal differences in magnitude, especially over two polar areas.