Graft lesions after coronary artery bypass graft are the common phenomenon. Thrombosis, endothelial dysfunction, vasospasm, and oxidative stress are important mechanisms leading to the lesions. Compared with arterial bypass graft, venous bypass graft is more susceptible to lesions, which is closely related to the anatomical morphology and functional characteristics of veins themselves. Acute thrombosis, intimal hyperplasia and vulnerable plaque formation are important mechanisms of vein graft lesions during different stages. Secondary prevention drugs such as antiplatelet and lipid-lowering drugs can improve the patency rate of bypass grafts. The search for predictors and related gene pathways of vein graft disease is expected to provide new research directions for vein graft disease at cellular and molecular levels. The review summarizes the research progress on pathogenesis of vein bypass graft stenosis and new vulnerable plaque lesions after coronary artery bypass graft.