一种自动追踪防撞警示方法，其包含下列步骤：借由至少二摄影单元截取一本车前方之影像；将该影像发送给一演算总成，借以将该影像由一三原色之影像转变为一灰阶之影像；借由该灰阶之影像，进而得出一该本车与该前车的相对车速；以及该演算总成依据该相对车速，进而得出一安全距离，若该安全距离大于本车与该前车之间的距离，则一警示模块即产生一警示消息。

An automatic tracking collision avoidance method has following steps: taking images in front of an origin car by at least two photograph units; the images delivering to a calculation assembly, to transform the images from three primary colors images to grey images; having a relative car speed of the front car corresponded to the original car according to the grey images; and according to the grey images the calculation assembly having a relative car speed that the front car corresponded to the original car; the calculation assembly having a safety distance according to the relative car speed, if the safety distance is great than a a distance that between the original car and the front car, a warming module generating a warming message.