Aiming at the infrared ship target detection against the background of sea, a saliency detection method based on frequency modulation is improved. First, a Gauss high pass filter is used to process an infrared image, so as to restrain the effect of sea clutter. Then, the saliency detection method based on frequency modulation is used to detect the ship target. The result shows that the infrared ship target is more complete when it is detected by the proposed method. The resolution of the saliency figure obtained is higher. The method can meet the real-time requirement.