The enhancement of infrared images containing sea and sky requires not only to remove effects by heavy wind and waves, but also to enhance target region’s contrast. Exploring several typical image enhancing algorithms, and combining the characteristics of infrared image’s histogram of gradient magnitude, an algorithm based on the infrared image’s gradient domain is proposed. Low magnitude is set to zero to reduce wave disturbance, gradient magnitude range is adjusted to control brightness, and valid gradient magnitude range is equalized to enhance target region’s details. Experimental results show that the proposed algorithm can obviously reduce the interference information of the image and improve the contrast and information entropy of target region.