The effect of solvent component on the discharge performance of lithium–sulfur (Li/S) cell and the optimal composition of ternary electrolyte for the improved discharge performance of the cell have been investigated. The capacity value and capacity stability with cycle are dependent on the nature of solvent as well as the composition of mixed solvent. The change trend of discharge performance as a function of content of each solvent component is studied. Capacity value increases as the 1,3-dioxolane (DOX) content decreases. Average discharge voltage shows larger value when the 1,2-dimethoxy ethane (DME) content is small. Finally, we have obtained the optimal solvent composition by using a statistical method.