A lane departure warning system and method. The lane departure warning system includes an image sensing unit, an edge extracting unit, a lane recognizing unit, a lane type determining unit, a lane color detecting unit, a lane pattern generating unit, and a lane departure determining unit. The image sensing unit senses a plurality of images. The edge extracting unit emphasizes edge components necessary for lane recognition. The lane recognizing unit detects straight-line components. The lane type determining unit determines a type of the lane. The lane color detecting unit detects a color of the lane from an image signal value. The lane pattern generating unit generates a lane pattern. The lane departure determining unit determines lane departure in consideration of the type and the color of the lane and a state of a turn signal lamp.