A touch display panel and a display device are provided. The touch display panel includes a color filter substrate, an array substrate, a back light source arranged below the array substrate and a liquid crystal layer arranged between the color filter substrate and the array substrate. The color filter substrate includes a black matrix. The touch display panel further includes an optical sensor arranged between the color filter substrate and the liquid crystal layer or between the array substrate and the liquid crystal layer, and is configured to detect light emitted by the back light source, propagating through the liquid crystal layer, and then arriving at a light detection surface of the optical sensor, to acquire detection data for determining a position of a touch operation performed on the touch display panel.