Abstract: A platinum-based drug/photosensitizer-loaded protein nanoparticle, and a preparation method therefor and an application thereof. The platinum-based drug/photosensitizer-loaded protein nanoparticle includes a platinum-based drug/photosensitizer complex, and a protein that encapsulates the platinum-based drug/photosensitizer complex. The prepared nanoparticles have a small particle size, are evenly dispersed and round in shape, and have good chemical stability, light stability, and high active oxygen generation capability when irradiated by near-infrared light; in cell experiments and animal experiments, it is verified that strong cytotoxicity to tumor cells and good in vivo tumor targeting are achieved, a synergistic effect is exerted, toxic and side effects are reduced, the use of chemotherapy and photodynamic therapy in combination to treat tumors is achieved, and metastasis of tumors is inhibited.