Abstract: Metabolic syndrome (MS) refers to the pathological condition with abnormal accumulation of various metabolic components, and typical diseases are atherosclerosis (AS), type II diabetes, obesity and non-alcoholic fatty liver disease (NAFLD). Recently, several studies have shown that TREM2 (triggering receptor expressed on myeloid cells 2) is highly expressed in lipid-associated macrophages (LAMs) and Kupffer cells (KC) in NAFLD, as well as aortic macrophages in AS, showing its close and complex relationship with metabolic syndrome. This review focuses on the roles and mechanisms of TREM2 in metabolic syndrome including NAFLD, diabetes and AS, with the hope to provide some new strategies for treatment of metabolic syndrome by targeting TREM2.