Abstract: The invention discloses an object-detecting system including a periphery member, a first reflection device, a first image-capturing unit, and a data processing module. The periphery member thereon defines an indication space and an indication plane in the indication space for an object to indicate a target position. There is a contrast relation between the periphery member and the object. The first reflection device is disposed on the periphery member. The first image-capturing unit captures a first image of the indication space near a part of the periphery member and also captures a first reflected image reflected by the first reflection device of the indication space near a part of the periphery. The data processing module is electrically connected to the first image-capturing unit and processes the first image and the first reflected image so as to determine object information relative to the object in the indication space.