Washing oil fractions are 230 ~ 300 ℃ distillation fractions in the distillation process of coal tar, their contents are commonly between 6.5% ~10% of coal tar. Wash oil fractions are mainly used in washing, absorption of various kinds of organic gas in coke oven gas, and separation and extraction of oxygen fluorene, naphthalene, quinoline, alpha methyl naphthalene, biphenyl and other basic organic chemical raw material products. The uses of washing oil fractions，the significance and technologies of preliminary separation of wash oil fractions were introduced.It was put forward after wash oil fractions were separated and refined， not only a rich variety of chemical products with high added value could be got, but also benzene hydrocarbon sorbent intermediate wash oil with good absorbed effect could be got，so it was of great significance to the preliminary separation process of wash oil fractions.