The development of electrocatalysts with high catalytic activity is conducive to enhancing polysulfides adsorption and reducing activation energy of polysulfides conversion, which can effectively reduce polysulfide shuttling in Li-S batteries. Herein, a novel catalyst NiCo-MoO_x/rGO (rGO = reduced graphene oxides) with ultra-nanometer scale and high dispersity is derived from the Anderson-type polyoxometalate precursors, which are electrostatically assembled on the multilayer rGO. The catalyst material possesses dual active sites, in which Ni-doped MoO_x exhibits strong polysulfide anchoring ability, while Co-doped MoO_x facilitates the polysulfides conversion reaction kinetics, thus breaking the Sabatier effect in the conventional electrocatalytic process. In addition, the prepared NiCo-MoO_x/rGO modified PP separator (NiCo-MoO_x/rGO@PP) can serve as a physical barrier to further inhibit the polysulfide shuttling effect and realize the rapid Li⁺ migration. The results demonstrate that Li-S coin cell with NiCo-MoO_x/rGO@PP separator shows excellent cycling performance with the discharge capacity of 680 mAh·g⁻¹ after 600 cycles at 1 C and the capacity fading of 0.064% per cycle. The rate performance is also impressive with the remained capacity of 640 mAh·g⁻¹ after 200 cycles even at 4 C. When the sulfur loading is 4.0 mg·cm⁻² and electrolyte volume/sulfur mass ratio (E/S) ratio is 6.0 μL·mg⁻¹, a specific capacity of 830 mAh·g⁻¹ is achieved after 200 cycles with a capacity decay of 0.049% per cycle. More importantly, the cell with NiCo-MoO_x/rGO@PP separator exhibits cycling performance under wide operating temperature with the reversible capacities of 518, 715, and 915 mAh·g⁻¹ after 100 cycles at −20, 0, and 60 °C, respectively. This study provides a new design approach of highly efficient catalysts for sulfur conversion reaction in Li-S batteries.