Abstract: Photodynamic therapy (PDT) is an important method for tumor treatment. Light, photosensitizer and oxygen are the three key elements in PDT. At present, the efficacy of PDT in treating deep solid tumor is not satisfactory due to the insufficient tissue penetration depth of ultraviolet or visible light (classic PDT light source for small molecule photosensitizers), hypoxic microenvironment of solid tumor tissues, limited tumor targeting ability, insufficient photo-stability and reactive oxygen generation capacity of small molecule photosensitizers. In recent years, various functional nanomaterials with excellent optical properties, catalytic properties and satisfactory reactive oxygen species generation capability have been invented and were used to construct new nano-photodynamic therapy systems in order to solve the bottleneck in their application in deep solid tumors treatment. From the perspective of the three key elements of photodynamic therapy, this paper reviewed the recent progress in nanomaterials whose design and synthesis are based on the three key elements and their application in the photodynamic therapy for tumor.