Photodynamic therapy is a noninvasive therapy of cancers that utilizes exogenous visible, near-infrared light to induce the photosensitizer to react with molecular oxygen to produce a highly active photochemical product of reactive oxygen species which can induce apoptosis or necrosis of tumor cells, with low immunogenicity, low cost, high selectivity and other characteristics. Photodynamic therapy has become a hot topic in the basic research and clinical transformation of cancer treatment. However, the decreased effect of photodynamic therapy induced by tumor-microenvironment factors and the tolerance of tumor cells hinder the development of photodynamic therapy and clinical application. With the rapid development of comprehensive fields such as nanotechnology and biomedical engineering, and the deepening study of tumor microenvironment, the tumor-microenvironment activable smart nanocarrier system for the diagnosis and the synergistic treatment of cancer draw high attention in recent years. Based on this, the research of tumor-microenvironment activable smart nanocarrier system is reviewed to provide a reference and a new research idea for photodynamic therapy of tumors.