In order to enhance the e.ect of photosensitizer photodynamic therapy on leukemia, the photocatalytic inactiva-tion e.ects of composite nanoparticles FA-CS@Fe-TiO2 on HL60 cells were studied. The composite nanoparticles FA-CS@ Fe-TiO2 were formed by the modi.cation of tumor-targeting molecule folic acid (FA), plus Fe-TiO2 was wrapped by chitosan nanoparticles (CS-NP). FA-CS@Fe-TiO2 nanoparticles were prepared by sol-gel method, two-step method, and surface modi-.cation method, and analyzed by X-ray di.raction (XRD), scanning electron microscopy (SEM), and Fourier infrared spec-troscopy. The CCK-8 method and active oxygen content analysis method were used to analyze the mechanism of FA-CS@Fe-TiO2 photocatalytic inactivation of HL60 cells. Cell test results showed that under non-light conditions, chitosan (CS) itself had no obvious inhibitory e.ect on cell growth, and it had a certain promotion e.ect on cells at low mass concentrations of 5 μg/mL. Compared to Fe-TiO2 and FA-CS@Fe-TiO2 nanomaterials, the toxicity of CS@Fe-TiO2 was signi.cantly reduced, and even at a high quality concentration of 160 μg/mL, the relative survival of HL60 with CS@Fe-TiO2 (3:2) can still be as high as 85%, which indicates that the coating of chitosan can improve the biocompatibility of the composite nanoparticles. Photodynamic therapy (PDT) tests have shown that folic acid modi.cation can signi.cantly increase the uptake of composite nanoparticles by HL60 cells and enhance its inactivation e.ciency to HL60 cells. The highest PDT inactivation e.ect of FA-CS@Fe-TiO2 nanoparticles was 78.75%. It provides a reference for the clinical application of photodynamic therapy in the treatment of leukemia tumor cells.