Endostatin (ES) is a naturally occurring, 20kDa C-terminal fragment derived from type XVIII collagen. It is reported to serve as an anti-angiogenic agent, similar to angiostatin and thrombospondin. Endostatin is a broad-spectrum angiogenesis inhibitor and may interfere with the pro-angiogenic action of growth factors such as basic fibroblast growth factor (bFGF/FGF-2) and vascular endothelial growth factor (VEGF). To test the effect of ES on inhibit the VEGF basic-dependent proliferation of ECV304 endothelium cell line, cells were seeded into triplicate wells of 96-well plates at a density of 5, 000 cells/well when the cell attached, replaced with serum-free standard DMEM overnight. Then the medium was replaced with 2% serum standard DMEM which contain 10ng/mL of VEGFA and various concentrations of ES. After incubated for 72h, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10µL of CCK-8 solution was added to each well of the plate, then measure the absorbance at 450nm using a microplate reader after incubating the plate for 1-4 hours at 37℃. The result was shown in Figure 1. It was obvious that ES (100ng/mL) significantly inhibit cell proliferation of EV304 cells.