An optical touch panel including a light guide plate, at least one light-emitting element and a plurality of optical sensing elements and a touchscreen using the same are provided. The light guide plate has a plurality of lateral surfaces, a top surface, a bottom surface and a light extraction structure. The light-emitting element provides a light beam entering the light guide plate. The optical sensing elements are disposed under the bottom surface of the light guide plate. Each of the optical sensing elements has a sensing surface not parallel to the bottom surface of the light guide plate. The optical sensing elements are disposed at an illuminated region of the light beam provided by the light-emitting element. By the light extraction structure, a second portion of the light beam entered the light guide plate is scattered to the optical sensing elements from the bottom surface.