The embodiment of the invention discloses a radio-frequency front-end device, an antenna device and a mobile terminal. A straight-through input end of a power coupler is connected with an uplink interface for transmitting an uplink signal; a straight-through output end of the power coupler is connected with an antenna; an isolating end of the power coupler is connected with a ground wire; a coupling output end of the power coupler is connected with a first end of a switch module through an attenuator; the coupling output end of the power coupler is also directly connected with a second end of the switch module; a third end of the switch module is connected with a power detection pin of a radio-frequency transceiver; if a first wireless communication module transmits a first uplink signal, the first end of the switch module is connected with the third end of the switch module, and the second end is disconnected with the third end; and if a second wireless communication module transmits a second uplink signal, the second end of the switch module is connected with the third end, and the first end is disconnected with the third end. Through adoption of the radio-frequency front-end device, power detection of a plurality of uplink signals transmitted by a plurality of wireless communication modules is considered.