More and more studies have shown that the intestinal microbiota are significantly associated with atherosclerosis. The nutrients such as lecithin, choline and carnitine in food are metabolized by the intestinal microbiota, and their metabolite trimethylamine-N-oxide (TMAO) may contribute to atherosclerosis. Its mechanism is not fully understood, but such a view provides a new orientation for research on atherosclerosis and other cardiovascular and cerebrovascular diseases. In this review, we summarized research on the mechanisms of TMAO-induced atherosclerosis in recent years.