Lithium-sulfur (Li-S) batteries are attractive candidates for advanced energy storage devices. However, the low utilization of sulfur and the severe "shuttle effect" hinder the commercialization of Li-S batteries. Herein, we design an ultra-thin and lightweight two-dimensional (2D) molybdenum nitride nanosheets layer to modify Celgard (denoted as MoNx/Celgard) separator to promote the electrochemical performance of Li-S batteries. Benefiting from the 2D polar molybdenum nitride nanosheets, the obtained molybdenum nitride layer can effectively suppress the shuttle effect via the synergistic effect of structural confinement and chemical absorption. Meanwhile, molybdenum nitride nanosheets layer possesses metallic and catalytic characteristics, which are beneficial for high sulfur utilization. Therefore, the Li-S batteries using MoNx/Celgard separator with multi-function exhibit high capacity and outstanding cycling performance. It delivers a high discharge capacity of 1298 mA h g(-1) at 0.1C and sustain a capacity of 566 mA h g(-1) after 500 cycles at 0.5C, corresponding with the capacity fading rate of only 0.063% per cycle.