A novel image-based landslide monitoring system proposed in this paper, which is using digital image processes methods to detect landslide occurred in any landslide occurred situation to achieve a non-contact landslide monitoring system by one image. The theory of this system is based on using a laser projector to project a laser beam to measurement box, which have two acrylic boards in the measurement box. When landslide occurred, the laser beam will generate two laser spots in image. To identify the coordinate of laser spots through an easy calculation, the system could get the landslide displacement and offset angle. According the measurement result, it could announce the warning and prevent the damage.