Optical touch display panel

The invention relates to an optical touch display panel which comprises a liquid crystal display panel, at least one sensing assembly and a side light-in backlight source. The sensing assembly is configured on the edge of the liquid crystal display panel. The side light-in backlight source is configured below the liquid crystal display panel and comprises a light guide plate, a plurality of first light sources, a plurality of second light sources and a plurality of auxiliary light sources. The light guide plate is positioned below the liquid crystal display panel. The sensing assembly corresponds to one corner of the light guide plate. The first light sources supply visible light for the light guide plate. The second light sources supply invisible light. The auxiliary light sources supply auxiliary invisible light and are configured at the rest corners of the light guide plate. When the liquid crystal display panel is touched, the invisible light and the auxiliary invisible light penetrating through the liquid crystal display panel are scattered, and the sensing assembly is suitable for sensing the scattered invisible light and the scattered auxiliary invisible light to calculate the position of a touch point.