Lactic acid is the main metabolic product of glycolysis and plays a vital role in energy supply and signal transduction. Lactate plays an important role in the development of a variety of diseases and promotes the progression of several types of tumours by inhibiting immune cells and creating an immunosuppressive microenvironment. The role of lactylation derived from lactic acid in gene transcription regulation and the modulation of protein structure and function was first reported in 2019 providing new insights into the role of lactate in physiological and pathological processes. This review retrospectively analyzes the published research on lactylation and summarizes the regulatory mechanisms of lactylation the histone lactylation sites and their regulatory role in the physiological and pathological processes of stem cells and embryonic development inflammation tumors and other diseases and the non-histone lactylation sites and their roles in physiopathology. Finally we summarise some of the unresolved issues in lactylation research. Lactylation is involved in the development of various diseases and targeting lactylation may serve as one of the strategies for clinical treatment of related diseases. However the regulatory mechanism of lactylation and its physiological regulatory role in the occurrence and development of diseases remains unclear and targeting lactylation is still in the theoretical stage. Further exploration of the mechanism and preclinical studies is needed to provide new view for the treatment of lactylation-related diseases.