A radio-frequency device includes a grounding element, a first antenna including a first parasitic element, a second antenna, a third antenna and a second parasitic element, wherein the grounding element is shared by the first, second and third antennas, the second parasitic element is electrically connected to the grounding element for guiding a first reflected signal from the first antenna to the second parasitic element, and the first parasitic element is electrically connected to the grounding element for guiding a second and third reflected signals from the second and third antennas to the first parasitic element, so as to enhance isolations of the first, second and third antennas.