The invention relates to an offshore image processing method based on global brightness adaptive equalization. The method comprises the steps of firstly, calculating a negation image of an offshore foggy day image; secondly, performing MSRCR operation on the original image and the negated image; then, carrying out the equalization processing by utilizing a global brightness adaptive histogram, andcarrying out low-frequency signal linear superposition on the processed brightness and a reflection component processed by the MSRCR; and finally, calculating a mean value and a standard deviation ofthe superposed images, and adopting an adaptive stretching image gray value to improve the image color contrast. According to the invention, the processed image has the advantages of prominent foreground, clear details and rich colors, and the method has the better application value for the offshore image defogging.