Endothelial progenitor cells (EPCs) were discovered in 1997 and brought new insights for angiogenesis. EPCs can differentiate into mature endothelium and take part in angiogenesis. Studies have found that EPCs is a promising candidate for treating cardiovascular disease. Aspirin has antiplatelet effect and is widely used for prevention of stroke and cardiac infarction. Low dose of aspirin can improve EPCs function through antiplatelet effect, improve endothelial function, and restore the endothelium-dependent vasodilatation. Therefore it is of great significance to understand the effect of aspirin on EPCs and the related mechanisms.