## 1 Introduction
[21] used a nanosecond pulsed fiber laser to clean a 20 um thick white polymer paint layer on an aluminum alloy substrate and studied the effect of overlap ratio, paint removal times, and pulse frequency on processing depth. In terms of the effect on the microstructure and properties of the substrate, [PERSON] et al. [22] studied the residual stress, micro-hardness, and corrosion performance of the aircraft skin surface after laser paint stripping. Compared with the mechanical lapping and laser paint stripping methods, it proves that the laser will not reduce the hardness and corrosion resistance of the aircraft skin. [PERSON] et al. [23] analyzed the effects of different laser energy densities on the surface morphology, surface composition, microhardness, and corrosion resistance of 7075 aluminum alloys. [PERSON] et al. [24] studied the removal of aluminum alloy oxide layers using laser cleaning technology. It was found that the laser cleaning technique effectively enhanced the tensile and bending properties of the aluminum alloy base metal and could expand the application of aluminum alloy in a high-speed rail. Laser cleaning technology mainly includes laser dry cleaning, liquid film-assisted laser cleaning, and laser shock wave cleaning [25]. Laser dry cleaning is the most widely used, but it is easy to produce sputtering risk and dust pollution in the cleaning process, and it will trigger thermally induced defects on the surface of the matrix material, which will manifest as a recast layer and heat-affected zone and have an adverse impact on the mechanical properties of the material. Liquid film-assisted laser cleaning of the liquid film requires more, for the stronger adhesion of contaminants cleaning is not ideal. Laser impact cleaning mainly relies on the role of shock waves in removing contaminants, which are usually applied in particle cleaning. In recent years, water jet-guided laser technology has achieved remarkable results in micro-processing, such as cutting and drilling metals, ceramics, semiconductors, and other materials [26; 27; 28]. In the area of water jet-guided laser cleaning technology, [PERSON] [29] used a fiber laser with a wavelength of 1070 nm to conduct paint removal experiments with the aid of water jets. It was found that the paint layer could be completely removed with the assistance of a water jet. Althoughnanosecond lasers are widely used in water jet-guided laser technology, their application has low cleaning efficiency and high cost, which limits its engineering application. In this paper, to solve the difficulties of quasi-continuous laser cleaning technology and the bottleneck of water jet-guided laser cleaning technology, a water jet-guided quasi-continuous laser cleaning technology is proposed innovatively. The resin-based coatings on the metal substrates were removed by the combined action of a quasi-continuous laser and a water jet. In this paper, the epoxy resin coating on the surface of 304 stainless steel is used as the cleaning object, the quasi-continuous laser is used to carry out the water jet-guided laser cleaning test, and the surface morphology, surface element content, and surface roughness of the cleaning area are tested and analyzed. The mapping relationship between the water jet-guided quasi-continuous laser cleaning process parameters (energy density of the water jet-guided laser, cleaning speed, cleaning line spacing, and laser frequency) and the surface quality after cleaning (surface morphology and surface roughness) is established. The influence of process parameters on surface quality is analyzed to provide a reference basis for the optimal selection of process parameters for water-guided laser cleaning.