Coals were extracted with a carbon disulfide-N-methyl-2-pyrrolidinone (CS2-NMP) mixed solvent at room temperature. The extraction residue was packed into a column, and inverse liquid chromatography (ILC) was carried out for standard polystyrenes with a wide range of molecular weight, using this column. The retention volume of polystyrenes was smaller than that of chloroform or benzene which was used as a carrier solvent except in a few cases and decreased with an increase in their molecular weight, suggesting that polystyrenes were separated by size exclusion mechanism. The extraction residue with high extraction yield (63 wt %) from Zao Zhuang coal separated the polystyrenes with molecular weight of 10(2)-10(7) and that with low extraction yield (5 wt %) did not separate well. polystyrenes higher than 10(4) molecular weight, suggesting that relatively large pores, which separate high molecular weight polystyrenes, would not be formed for the residue with low extraction yield. An extract fraction from Zao Zhuang coal, which is the CS2-NMP-soluble and pyridine-insoluble fraction (PI), also could separate polystyrenes by size exclusion mechanism. The size exclusion mechanism for this ILC was discussed.