A sensing system includes a panel, a reflective element, an image sensor, a processor, a first light guide rod, a second light guide rod and a light source module. The panel has a plane and a first area and a third area located at the plane. The third area in the first area is smaller than or equal to the first area. The first area has four boundaries connected in order. A reflective mirror plane of the reflective element disposed at the first boundary mirrors the first and third areas. The image sensor disposed at the intersection of the third and fourth boundaries is electrically connected to the processor. The first and the second light guide rods are disposed at the second and the third boundaries respectively. The light source module is adapted to emit light passing through the first and the second light guide rods to the image sensor.