After long-term operation of nuclear power plants, a large amount of impurities, corrosion activation products, fission products and other radioactive substances are easily deposited to equipment and pipelines. In order to reduce the on-site radioactivity and the collective dose of operators, in-situ radioactive decontamination of large-scale immovable components is required. Based on the strong focusing effect of cavitation energy, this study designed a cavitation jet decontamination equipment, including a cavitation jet nozzle, multi-degree of freedom robotic arm, contamination protection device, and secondary waste collection device. Moreover, the practical performance was evaluated by testing the cavitation area, surface roughness, and decontamination factor. The results showed that the equipment has the advantages of remarkable decontamination effect, short decontamination time, and small amount of secondary waste liquid, with decontamination factor up to 12.1. Thus, this study provides an innovative decontamination equipment design and process research basis for the in-situ decontamination of large-scale components during the maintenance of operating nuclear power plants.