A touch display panel includes a substrate, a display layer disposed on the substrate, an insulating layer disposed on the display layer, and a touch electrode layer directly contacting the insulating layer. The display layer comprises a first region, a second region, and a third region. The second region is located between the first region and the third region. The second region is foldable. The insulating layer has a first thickness corresponding to the first region and a second thickness corresponding to the second region. The first thickness is different from the second thickness. The insulating layer comprises a first layer, a second layer, and a third layer, wherein the second layer is disposed between the first layer and the third layer. The first layer and the third layer are formed of inorganic insulating materials, and the second layer is formed of organic insulating material.