An optical touch structure including a light guide element, a light source, a reflecting mirror, and an image sensor is provided. The light guide element has a light-emitting surface. The light guide element guides the light provided by the light source to the light-emitting surface. The extending direction of the reflecting mirror is substantially perpendicular to the light-emitting surface. The intersection of the reflecting mirror and the light guide element is defined as a first position. The light guide element and the reflecting mirror define a touch range. The image sensor is disposed on a second position opposite to the first position. The sensing area of the image sensor at least covers the touch range. When the proceeding path of the first direction light is shorter than that of the second direction light, the strength of the second direction light is larger than that of the first direction light.