Abstract: There are many kinds of different noises in underwater welding images, and image denoising is an important part of underwater welding automation. The noise caused by suspended impurities in water is a major one, so a hybrid processing algorithm was designed. Firstly, the morphology closed operation was used to identify the noise, and then the median filtering was used to process the identified noise points, and the corresponding pixels were updated at real time.Finally, a comparative experiment was carried out for the designed algorithm and other noise reduction algorithms. The results show that the proposed method can not only reduce the image sharpness, but also protect the edge of the image effectively.The processed image has higher energy gradient value and structure clarity value than that of other methods. It is beneficial to the subsequent recognition and extraction of weld center.