Abstract: HRGC-MS was applied to simultaneous determination of 17 polychloro- as well as 8 polybromo- substituted dibenzodioxins and dibenzofurans in edible oil. The oil sample was purified by passing through acid silica gel bed, multilayer silica gel column and Florisil column successively, in which eluants of n-C6H14, mixture of n-C6H14 and CH2Cl2 (97+3), mixture of n-C6H14+CH2CH2 (40+60) and CH2Cl2 in single were used respectively. The eluates used for GC-MS analysis. Detection limits (3S/N) found for the 25 compounds were in the range of 0.022 3-1.67 μg·L-1. Values of recovery found were in the ranges of 97.8%-118% with RSD′s (n=5) ranged from 4.9%-6.7% and 96.5%-113% with RSD′s (n=5) ranged from 6.6%-17%, for the polychloro-substituted compounds and polybromo-substituted compounds respectively.