It is provided a filtering circuit and a touch display device. The touch display device includes: a substrate; a common electrode arranged on the substrate; a signal source configured to provide a display signal or a touch signal; a filter capacitor including a first terminal and a second terminal, where a fixed electric potential is applied to the second terminal of the filter capacitor; and a control switch arranged between a common electrode lead and the first terminal of the filter capacitor to electrically connect/disconnect the filter capacitor with/from the common electrode lead. In a case that the signal source provides a display signal, the control switch is switched on to electrically connect the filter capacitor with the first node. In a case that the signal source provides a touch signal, the control switch is switched off to electrically disconnect the filter capacitor from the first node.