One of the major issues limiting the practical application of lithium-sulfur (Li-S) batteries is that the sluggish redox kinetics of polysulfide intermediates exacerbate the unavoidable “shuttle effect”, which causes low sulfur utilization, rapid capacity fade, and anode corrosion. Herein, we firstly add a novel type of electrolyte additive, biological reagents dithiothreitol (DTT), into the traditional electrolyte of Li-S batteries to suppress the “shuttle effect”. DTT is able to be stabilized in original electrolyte system at room temperature and selectively slice the -S-S- bonds of polysulfides. The electrochemical studies reveal DTT significantly accelerate the reactions kinetic in cycle process and thus effectively inhibit the shuttling of polysulfides. As a result, the hierarchical porous carbon/S cathode using the electrolyte with 10 g L−1 DTT exhibits a high rate performance (570 mA h g−1 improved from 317 mAh g−1 at 3 C), a high initial discharge capacity (808 mAh g−1 at 0.5 C), and a superior cyclic stability (a low capacity fading rate of 0.025% per cycle over 500 cycles at 2 C). This strategy provides a new direction for achieving high energy density Li-S batteries and thus facilitating their practical application from the point of improving the kinetic sluggishness by electrolyte additive.