A Mn-clusters-porphyrin metal-organic framework nanosheet(nMn-MOF)was synthesized by coordination chelation to enhance photodynamic therapy. The nanosheet was characterized by dynamic light scattering, transmission electron microscopy and X-ray photoelectron spectroscopy. Oxygen sensor and ICG were used to investigate the production of oxygen and the singlet oxygen(1O2)generation. The cytotoxicity of the nanosheet against tumor cells were detected by CCK-8 assay, and the anti-hypoxia and oxygen-generation ability of nanosheets were investigated by fluorescence staining assay. The results indicated that this nanosheet could catalyze the intracellular H2O2 into O2, which overcame the tumor hypoxia. Furthermore, the generated oxygen was converted to cytotoxic 1O2 under the near infrared light irradiation, thereby enhancing photodynamic therapy.