Light cycle oil (LCO) contains a lot of valuable aromatic components, including 2,6-dimethylnaphthalene (2,6 DMNA) that is focused as the elementary raw material for engineering plastic (PEN plastic) and polymer liquid crystal etc. We investigated the separation and purification of 2,6-dimethylnaphthalene (2,6-DMNA) from LCO by distillation-extraction-crystallization combination. The process for the separation and purification of 2,6-DMNA from LCO was investigated by using the results obtained from the distillation, the extraction and the crystallization. The suggested process was composed of the distillation column (two) for recovering the distillate including DMNA isomers of high concentration, the extraction column (one) for separating between the paraffin components and the aromatic components in the distillate, the washing column (one) for recovering the paraffin components in the raffinate phase, and the distillation column (two) for recovering water and DMF in the solvent, the crystallization column (two) for high-purity purification of 2,6-DMNA, the distillation column (two) for recovering the solute crystallization solvent, the washing column (one) for washing the crystal, and the distillation column (one) for recovering the washing solvent. The process proposed by this work is the new one, considerating the separation between the paraffin components and the aromatic components in the distillate, also, and the simple one without the re-extraction operation by using DMF as the extraction solvent of the distillate. Therefore, this proposed process would be more effective process than the previous process proposed by the combination of extraction-distillation-crystallization.