Touch display device, handwriting pen and detection method of handwriting pen

A touch display device, a stylus pen and a detection method of the stylus pen are provided, the touch display device includes a first sensing element, a flexible display and a second sensing element, and the flexible display is located below the first sensing element. The flexible display is located between the first sensing element and the second sensing element. The second sensing element comprises a pressure sensing layer and a reaction force layer, wherein the pressure sensing layer is located between the flexible display and the reaction force layer. Through a stylus pen with a non-conductive material, a first sensing element detects that signals corresponding to the stylus pen and fingers or palms have different polarities. By capturing the intersection area of the signals detected by the first sensing element and the second sensing element, the technical effect of distinguishing the touch signals of the finger and the handwriting pen can be achieved. Besides, the second sensing element is configured to