This invention is to provide a sound reproduction device including a tube, a loudspeaker and a resonance unit, wherein the loudspeaker includes a frame body having a side adjacent to a first diaphragm thereof peripherally fixed to a first opening of the tube, and the resonance unit includes a second diaphragm peripherally fixed to a second opening of the tube and a weighting element fixed at a central position of the second diaphragm. Thus, a closed resonance chamber is defined within the tube between the loudspeaker and resonance unit. When the loudspeaker is driven, the first diaphragm is vibrated and in turn vibrates air in front of the sound reproduction device to make sound and drives the second diaphragm to vibrate air behind the sound reproduction device synchronously in the same direction, thereby producing twice as strong low-frequency sound effect as a traditional sound reproduction device without a resonance unit.