The binding and catalyzing of soluble polysulfide species to prevent their shuttles and accelerate the polysulfides conversion kinetics is essential to achieve lithium-sulfur batteries with high rate capability and superior cycling stability. Here, earth-abundant and eco-friendly pyrite FeS2 supported on N-doped porous carbon sheets is firstly demonstrated to act as a reliable adsorbent and active electrocatalyst towards polysulfide redox reaction with the aid of theoretical calculation and a series of fundamental experiments, which results in fast conversion kinetics of polysulfide. A detailed dissolution-capture-transformation mechanism is proposed on the tri-phase interface among pyrite FeS2, conductive N-doped porous carbon sheets and polysulfide species. On this tri-phase interface, the soluble polysulfide species can be chemically anchored and subsequently transform to Li2S efficiently catalyzed by pyrite FeS2, while the porous N-doped porous carbon sheets serve as highly conductive substrates for the nucleation of Li2S deposition. Consequently, the lithium-sulfur batteries with the composite cathodes exhibits excellent electrochemical rate capability (475 mAh g−1 at 5 C) and cycling stability (783 mAh g−1 after 160 cycles). The merits of low cost, eco-friendly feature combined with high activity towards polysulfides conversion reaction endows the pyrite FeS2 a promising electrocatalyst in realizing advanced lithium-sulfur batteries.