The 304 stainless steel specimens were corroded in 3%NaCl solution, and then cavitation erosion experiments were performed on these specimens using an experimental rig that conformed to the ASTM G134 standard. The effects of both the corrosion time and erosion time on cavitation erosion were analyzed. The cavitation erosion characteristics were described via the mass loss, surface microstructure, three-dimensional surface morphology and microhardness. The results show that for the specimen corroded for 24 h, the stage of cavitation erosion attenuation commences at the cavitation erosion time of 120 min. In the early stage of cavitation erosion, erosion pits manifest small size and depth. In the later stage of cavitation erosion, the plastic deformation is intensified and large erosion pits are abundant. Microcracks expand along grain boundaries. Eventually, the interconnection between erosion pits incurs peeling-off of grain boundaries. The surface roughness increases with the cavitation erosion time. Compared to the corroded specimens, the non-corroded specimen demonstrates higher surface roughness after cavitation erosion. As the corrosion time increases from 24 h to 120 h and the cavitation erosion time is remained at 120 min, the plastic deformation is strengthened and microcracks emerge at grain boundaries. The 3%NaCl solution helps to suppress cavitation erosion. Nevertheless, as the corrosion time increases, the suppression effect attenuates.