Abstract: For SNR of sea-sky-line is low and there is a certain inclination so thay are difficult to extract, a new extraction algorithm was proposed. Firstly, the image preprocessing was taken by applying Laplacian template filtering to enhance waves on the surface, followed by order-statistics filters and morphologic closing. After the image preprocessing step, the SNR of sea-sky-line was enhanced. Finally, seeking for the inclined sea-sky-line by using a novel matrix, the matrix should be produced by scanning infrared image horizontally, the maximal element of the matrix identified the position and angle of the sea-sky-line. The experimental result shows that the method can locate sea-sky-line efficiently and correctly, requiring a few computation and be used for engineering applications. Innovations are the use of templates and morphological operators to improve SNR of sea-sky-line and find matrix can simply locate the position and angle of sea-sky-line, reducing the computational complexity.