Abstract: After the oil spill accident, effective monitoring of offshore oil films is an important guarantee for emergency disposal. A fast oil film identification method of shipborne navigation radar remote sensing image is proposed here. Firstly, the vertical noise detection operator and Otsu method are used to extract the co-frequency interference noises in the original image. Next, linear interpolation is applied to smooth the co-frequency interference noises. Then, the gray adjustment matrix and Contrast Limited Adaptive Histogram Equalization method are used to enhance the contrast around the oil films. Finally, the histogram bimodal method is applied globally to extract offshore oil films quickly. Compared with other global adaptive threshold methods, histogram bimodal method has strong applicability in oil film identification. Compared with the local adaptive threshold method, the proposed method has faster efficiency. The successful application of the proposed method will provide rapid data support service for the real-time treatment of oil spills.