Abstract: This paper mainly use fine-grained silica gel to separate saturated and aromatic hydrocarbon in oil or extraction.By experiment,the method can separate saturated and aromatic hydrocarbon completely.Isomeric hydrocarbon increased in saturated hydrocarbon,alkylbenzenes and monoaromatic steranes group are also entered into aromatic hydrocarbon completely.The method makes up the deficiency in common method to separate saturated and aromatic hydrocarbon.In order to verify the reliability of the experiment,the author made a precision experiment at the same time,the error no more than 5%,This proved that the experimental apparatus is stable and the results is credible.