The outdoor experiments at three wavebands (290, 320, and 355 nm) are carried out to study the reflection characteristics of seawater targets and oil spill targets (e.g., crude oil, heavy oil, diesel oil, gasoline, and palm oil). The relationship curves of upwelling radiation intensity and the oil-seawater contrast of the detected target with the solar altitude angle and azimuth angle are obtained. Results show that when the solar altitude angle is 40°--60°, the contrast ratio between crude oil and seawater is 14%--44%, that between dead oil and seawater is 15%--35%, that between gasoline and seawater is 12%--26%, that between palm oil and seawater is 15%--47%, and that between diesel oil and seawater is 3%--12%. These results indicate that the detection and identification of different oils can be realized at different solar altitude angles and azimuth angles by the combination of three wavebands, among which the ultraviolet waveband exhibits an outstanding advantage in the early detection and identification of oil spills on sea surface.