Abstract—Al has been widely used in many common products, such as household items, industrial products, and accessories. To respond to the increasing demand for its use, the enhancement of various properties of Al by adding different elements has been explored. As a result, numerous types of aluminum alloys have been developed, the addition of elements is a complex process, and the recycling of such alloys is difficult. In this study, the improvement of the residual stress of the surface of pure Al specimens by the multifunction cavitation (MFC) processing was investigated. In the MFC-processed pure Al, water jet peening always suppressed the erosion generated in the center part of the specimen surface and improved the residual stress applied to the specimen surface.