A touch display device includes a substrate, a display element layer, a composite substrate, a touch electrode and an adhesive layer. The display element layer is disposed on the substrate. The composite substrate includes a support layer and a moisture barrier layer. The moisture barrier layer is in direct contact with and covers a surface of the support layer. The display element layer is located between the substrate and the composite substrate. A moisture transmission rate of the moisture barrier layer is less than 1×10−2 g/m2/day. The touch electrode is disposed on the composite substrate. The adhesive layer is disposed between the display element layer and the composite substrate.