A method for sounding-interval adaptation using link quality for use in an apparatus is provided. The apparatus includes a sounding transceiver. The method includes the following steps: periodically transmitting a sounding packet to a beamformee through a downlink channel from the apparatus to the beamformee using a first sounding interval; in response to the sound transceiver successfully receiving a report packet from the beamformee to respond to the sounding packet, obtaining a current first channel profile from the report packet, and calculating a first LQ (link quality) value of the beamformee using the current first channel profile and a previous first channel profile; searching an LQ-mapping table using the first LQ value to obtain a second sounding interval; and adaptively adjusting the first sounding interval using the second sounding interval in response to a comparison result of the current first channel profile and the previous first channel profile.