Abstract: Paper chromatography of urea complexation is used to seperate chained-naphtene and n-alkane, which improved the method of 5 Amolecular sieve adsorption and simplified the complicated process of urea complexation. Based on the principle of urea complexing n-alkane, saturated solution of urea formaldehyde is directly spreaded on chromatographic paper with quick spatting. As a result, alkane and urea in the sample are complexed rapidly. Then n-alkane is seperated from alkyl component by drying and developing. Through experiments, it is proved that the method is easy in practice, and very effective.