The invention relates to a lithium battery with a polymer-coated sulfur/carbon composite material as an anode. According to the invention, sublimed sulfur or sulfur powder and a conductive carbon material are mixed according to a mass ratio of 3:7-8:2; the mixture is subject to ball milling, such that a sulfur/carbon composite material is obtained; the composite material is dispersed in a solution, and a polymer monomer is added to the solution; under a low temperature and the protection of inert gas, an oxidizing agent is added for initiating polymerization; the material is centrifuged, washed, and dried; the obtained polymer-coated elemental sulfur/carbon composite material, acetylene black and PTFE are mixed; a dispersant is added to the mixture, and the mixture is sufficiently mixed by stirring; the mixture is rolled into a sheet, and is vacuum-dried under a temperature of 55 DEG C, such that an electrode sheet is obtained. The prepared electrode sheet is adopted as an anode, metal lithium is adopted as a cathode, and a solvent type organic solution system containing 0.2mol/L of a waterless lithium nitrate additive is adopted as electrolyte, and a battery is assembled. With the electrode material, the assembled lithium battery is advantaged in high specific capacity, good circulation stability, and excellent heavy-current charge/discharge performances. The preparation method is advantaged in simple process, low cost, and good repeatability.