Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase consisting of three subunits, namely A, B and C. Studies have shown that PP2A plays an important role in energy metabolism, DNA damage and repair, protein translation, cell cycle regulation and signal transduction by catalyzing the dephosphorylation of proteins and participating in the regulation of a variety of enzymes and transcription factors. This article reviews the structure and regulation of PP2A, its effect on energy metabolism and the occurrence of related diseases.