S0.87Se0.13/CPAN (carbonized polyacrylonitrile) composites material was synthesized by annealing the mixture of S (sulfur), Se (selenium) and PAN directly at 400 °C. The prepared composites was used as high capacity and stable cycling performance cathode for lithium sulfur battery. It delivers a specific capacity of 1210 mAh g−1 after 100 cycles at a constant current density of 120 mA g−1. In addition, it remains 989 mAh g−1 after 200 cycles at a current density of 300 mA g−1 with ultralow capacity fading of 0.025% per cycle. Meantime, the S0.87Se0.13/CPAN cathode exhibits extremely low self-discharge behavior. The superior electrochemical performance of S0.87Se0.13/CPAN composites should be ascribed to high S/Se ratio in S0.87Se0.13/CPAN composites and good conductivity brought by the addition of Se, which make full use of high capacity of S. Moreover, the chemical bonding between Se and S, as well as the chemical bonding between S0.87Se0.13 and CPAN decrease the loss of active material. This easy one-step synthesis procedure offers a feasible new route for the development of sulfide-based cathode material.