In order to realize the fast and non-contact detection of oil film thickness on water surface, a system based on laser Raman spectroscopy technologywas introduced in this paper. The 532 nm laser was used as the exciting source, and the result shows there is obvious difference between the Raman spectra of diesel and gasoline on water surfacewhich have the same oil film thickness, the spectral intensity of 97# gasoline is stronger than that of 90# gasoline at 1 651 cm-1. With the increase of oil film thickness, the spectral intensities of 316, 1 451 and 1 651 cm-1 are enhanced, the calculation factor rfilm of oil film thickness shows a decreasing trend. The experiment result shows that the Raman spectroscopy can be used as a reference for oil film thickness inthe application.