Hyperspectral data of thin oil slicks have some spectral response characteristics, and an experiment of offshore thin oil slicks was designed to measure and analyze their reflectance by using ASD hyperspectral instrument. With the oil slick thickness changing, its color varied from rainbow sheen slick to fuchsine sheen slick, kelly sheen slick, aqua sheen slick, silver sheen slick and light sheen slick. The result suggested that different thin oil slicks have different characteristics, some thin oil slicks could change the reflectance at 440 nm which is the spectral absorption peak value of chlorophyll, and the best hyperspectral band to distinguish the different offshore thin oil slicks is located in the range between 350 and 440 nm. The reflectance of thin oil slicks is higher than that of seawater in the hyperspectral data range from 440 to 900 nm, but has no absorption or reflection characteristics compared to seawater’s. It could not be detected in the range of near infrared from 900 to 2 500 nm of offshore thin oil slicks because of high noise, low signal and influence of the atmosphere. Finally, the spectral response theory of offshore thin oil slicks was analyzed, and the results indicated that the interference phenomenon of offshore thin oil slicks could add reflected light and change the reflectance of seawater, hence, increase the feasibility of offshore oil slick remote sensing.