The invention discloses a diaphragm-voice coil assembly and system and a method for adjusting the balance of a vibrating voice coil. The diaphragm-voice coil assembly comprises a diaphragm, a vibrating voice coil and a magnetic sensor, wherein the diaphragm comprises a diaphragm body and a DOME fixed on the plane portion of the diaphragm body; the vibrating voice coil is fixed on one side of the diaphragm body; and the magnetic sensor can measure and acquire magnetic induction intensity, and is fixed on the diaphragm. The magnetic sensor capable of acquiring the magnetic induction intensity is arranged on the diaphragm of the diaphragm-voice coil assembly, the relative position of the vibrating voice coil in a magnetic gap can be monitored via the magnetic induction intensity, and the relative position of the vibrating voice coil in the magnetic gap can be adjusted according to the position information of the vibrating voice coil by changing the pressure in a rear vocal cavity or changing the direct current in audio signals or the like, so that a loudspeaker is maintained in a lowest distortion state.