Metabolic disorders are a common feature of tumor cells. Pyruvate kinase M2 (PKM2) is a key regulator of aerobic glycolysis in tumor cells. PKM2 expresses specifically in tumor cells and provides energy required for tumor cell growth, as well as materials for synthesis of biological macromolecular substances. PKM2 can not only express in the cytoplasm, but also enter tumor cell nucleus and act as a protein kinase, which can promote the proliferation of tumor cells. Tumor cells can regulate the expression of PKM2 via many ways, such as allosteric effect, transcription regulation, post-transcriptional modification, and interaction between proteins. PKM2 is not only an important kinase for regulating tumor metabolism, but also an important factor for regulating tumor growth. It is expected to play a crucial role in diagnosis and targeted therapy of tumor.