A switch device comprising: a first node located on a first path formed between a first signal transceiving terminal and a second signal transceiving terminal; a first switch unit comprising a first terminal coupled to the first node, a control terminal, and a second terminal; an adjustment switch comprising a first terminal coupled to the second terminal of the first switch unit, a control terminal, and a second terminal coupled to a reference voltage terminal; an impedance element comprising a first terminal coupled to the first terminal of the adjustment switch, and a second terminal coupled to the second terminal of the adjustment switch; a second node located on a second path formed between the first node and the reference voltage terminal; and a detection unit configured to detect a node signal at the second node and control the first switch unit and the adjustment switch according to the node signal, and the detection unit comprising a first input terminal coupled to the second node, a first output terminal coupled to the control terminal of the first switch unit, and a second output terminal coupled to the control terminal of the adjustment switch; wherein: the detection unit detects the node signal for detecting mismatch between impedances corresponding to the first signal transceiving terminal and the second signal transceiving terminal, and the mismatch is detected by whether a rectified and low-pass filtered node signal is stronger than a predetermined value; and the switch device further comprises: a direct-current blocking capacitor coupled between the second terminal of the first switch unit and the first terminal of the adjustment switch. a first node located on a first path formed between a first signal transceiving terminal and a second signal transceiving terminal; a first switch unit comprising a first terminal coupled to the first node, a control terminal, and a second terminal; an adjustment switch comprising a first terminal coupled to the second terminal of the first switch unit, a control terminal, and a second terminal coupled to a reference voltage terminal; an impedance element comprising a first terminal coupled to the first terminal of the adjustment switch, and a second terminal coupled to the second terminal of the adjustment switch; a second node located on a second path formed between the first node and the reference voltage terminal; and a detection unit configured to detect a node signal at the second node and control the first switch unit and the adjustment switch according to the node signal, and the detection unit comprising a first input terminal coupled to the second node, a first output terminal coupled to the control terminal of the first switch unit, and a second output terminal coupled to the control terminal of the adjustment switch; wherein: the detection unit detects the node signal for detecting mismatch between impedances corresponding to the first signal transceiving terminal and the second signal transceiving terminal, and the mismatch is detected by whether a rectified and low-pass filtered node signal is stronger than a predetermined value; and the switch device further comprises: a direct-current blocking capacitor coupled between the second terminal of the first switch unit and the first terminal of the adjustment switch. the detection unit detects the node signal for detecting mismatch between impedances corresponding to the first signal transceiving terminal and the second signal transceiving terminal, and the mismatch is detected by whether a rectified and low-pass filtered node signal is stronger than a predetermined value; and the switch device further comprises: a direct-current blocking capacitor coupled between the second terminal of the first switch unit and the first terminal of the adjustment switch.