Triggering receptor expressed on myeloid cells 2 is a lipid-sensing immune receptor expressed on the surface of myeloid cells. In recent years, with the advancement of single-cell RNA sequencing technology, researchers have identified a macrophage subset characterized by high TREM2 expression within atherosclerotic (AS) plaques. This subset plays a vital role in lipid metabolism, efferocytosis, inflammatory regulation and the maintenance of plaque stability.Accumulating evidence indicates that TREM2 exhibits prominent functional heterogeneity across different stages of atherosclerosis. In the early stage of the disease, TREM2 accelerates plaque progression by facilitating lipid uptake and foam cell formation. In the late stage, however, it alleviates necrotic core formation and promotes plaque stability by enhancing efferocytosis, maintaining metabolic homeostasis of macrophages and curbing excessive inflammation.This article reviews the molecular structure and signal transduction of TREM2, the transcriptional profiles of TREM2-high macrophages, as well as the stage-specific functional mechanisms of TREM2 in atherosclerosis, aiming to provide novel theoretical evidence and potential therapeutic targets for immunometabolic intervention against atherosclerosis.