A double-layer dumb drum with a sand belt adjusting function includes an upper-layer elastic body, a strike edge, an upper bottom plate, a sand belt adjusting device, an internal resonance chamber, an external resonance chamber, a lower-layer elastic body, and a lower bottom plate. The upper-layer elastic body is fixed to the top of the upper bottom plate; the internal and external resonance chambers are under the upper bottom plate; the sand belt adjusting device is installed in the internal resonance chamber; and the bottom of the internal resonance chamber is sealed by the external resonance chamber. A lower-layer elastic body is fixed to the top of the lower bottom plate; contact points are at the bottom of the external resonance chamber and abut against the top of the lower-layer elastic body; and connecting screws are connected between the upper and lower bottom plates.