The invention relates to a double-rack driven lead damper provided with a rotary gear with inner square slots. The lead damper comprises a cavity, racks, the gear with the inner square slots, a spline shaft, a flange and the like, wherein the spline shaft is arranged at the center of the gear with the inner square slots, and spline slots are formed in a spline shaft body; the flange is welded and sealed at the front end of the gear with the inner square slots; lead is poured into a gap between the spline shaft and the gear with the inner square slots through hole communicating the spline shaft and the spline slots; the front end and the rear end, extending out of the gear with the inner square slots, of the spline shaft are welded on a front side plate and a rear side plate. When the upper rack and the lower rack perform stretching and reciprocating motion, the upper and lower racks and teeth of the gear with the inner square slots are meshed for transmission, the gear with the inner square slots is driven to rotate, lead between the gear with the inner square slots and the spline shaft is driven to realize plastic deformation through reciprocating rotation of the gear with the inner square slots, and accordingly, the energy is dissipated.