Abstract: Features of optical image target obtained by imaging anti-ship missiles are studied, and an algorithm to locate the naval ships on sea-sky-line is presented. Firstly, the image preprocessing is taken by applying Canny edge detection and OTSU algorithm. Then the sea-sky-line and naval ships upon edges are obtained by projection. The sea-sky-line equation is reached using one-dimensional linear regression equation. The naval ships positions can finally be located from the sea-sky-line area. The experimental result showed that the method can locate the naval ships positions from the sea-sky-line area efficiently and correctly, requiring less time than existing methods.