Disclosed are a headset device, a headset, and a method for processing a signal by the headset device. The headset device comprises: a first interface, a second interface, a switch and an isolation unit. The isolation unit comprises a first isolation body and a second isolation body connected to the first isolation body in parallel. The first interface is connected to the second interface through the isolation unit, wherein the first interface is configured to connect to a ground network of the headset, and the second interface is configured to connect to a ground line of a mobile terminal where the headset device is located. Through the disclosure, FM interference is reduced while TDD noise interference is reduced, thus user experience is improved.