In recent years, oil spill accidents occur frequently in the marine area of China. Finding out the spilled oil source is a key step in the relevant investigation. In this paper, a step-by-step fingerprinting identification method was used in a spilled oil accident in the Bohai Sea in 2002. Advanced chemical fingerprinting and data interpretation techniques were used to characterize the chemical composition and determine the possible sources of two spilled oil samples. The original gas chromatography -flame ionization detection (GC-FID) chromatogram of saturated hydrocarbons was compared. The gas chromatography-mass spectrometry (GC/MS)chromatograms of aromatic hydrocarbons terpane and sterane, n-alkane and poly-aromatic hydrocarbons (PAHs) were analyzed. The correlation analysis on diagnostic ratios was performed with Student's t-test. It is found that the oil fingerprinting of the spilled oil (designated as szl) from the polluted sand beach was identical with the suspected oil (designated as kyl) from a nearby crude oil refinery factory. They both showed the fingerprinting character of mixed oil. The oil fingerprinting of the spilled oil (designated as msl) collected from the port was significantly different from oil kyl and oil szl and was with a lubricating oil fingerprint character. The identification result not only gave support for the spilled oil investigation, but also served as an example for studying spilled oil accidents.