The utility model provides a passive bass auxiliary sound box. The loudspeaker box is characterized in that the four single loudspeakers are respectively bonded in four grooves of the upper shell, internal supports of the four single loudspeakers are respectively provided with two bonding pads, the four single loudspeakers are divided into two pairs, and a lead is arranged between the two single loudspeakers of each pair of single loudspeakers and welded on the bonding pads so as to connect the two single loudspeakers in series. Connecting the bonding pads of the four single loudspeakers through terminal wires to connect the four single loudspeakers in parallel; passive films are pasted in the two runway-shaped grooves of the lower shell; the upper shell and the lower shell are ultrasonically welded into an outer shell. According to the novel sound box with the passive bass auxiliary function, the low-frequency sound effect can be improved on the premise that the medium-high frequencysound effect is not weakened, the internal single loudspeakers are assembled in a bonding pad mode, and installation is more convenient and simpler.