An interactive touch system includes a display device, a light source device and an invisible light detecting device. The display device is adapted to provide an image beam to a display surface. The light source device includes a light-emitting element and a light-guide element. The light-guide element has a conical surface and a cylindrical curved surface facing the conical surface. The curvature center of at least partial section of the cylindrical curved surface is not located on the central axis of the conical surface. The light-emitting element is adapted to emit an invisible light beam toward the conical surface, and the invisible light beam is reflected by the conical surface and the cylindrical curved surface to be diverged and range over the display surface. When an object moves to the display surface, the invisible light beam is reflected by the object to be detected by the invisible light detecting device.