An organic anti-reflective polymer having the following Formula 1, its preparation method, an anti-reflective coating composition comprising the organic anti-reflective polymer and a preparation method of an anti-reflective coating made therefrom. The anti-reflective coating comprising the polymer eliminates standing waves caused by the optical properties of lower layers on the wafer and by the thickness changes of the photoresist, prevents back reflection and CD alteration caused by the diffracted and reflected light from such lower layers. Such advantages enable the formation of stable ultrafine patterns suitable for 64M, 256M, 1G, 4G, and 16G DRAM semiconductor devices, improving the production yields and controlling the k values. It is also possible to prevent undercutting due to an unbalanced acidity after finishing the coating.