The invention discloses a lithium-sulfur battery adopting a multi-layer composite separator. The multi-layer composite separator is characterized in that one side surface of a substrate separator is coated with a polymer layer A, the other side surface of the substrate separator is coated with an inorganic solid material layer and a polymer layer B, and the inorganic solid material layer is located between the substrate separator and the polymer layer B. The mechanical strength of the separator can be improved by the inorganic solid material layer, when a ceramic material with a lithium ion conduction function is used, the ionic conductivity of the separator can be improved effectively, and a polarization effect in charge-discharge processes is reduced. An electrolyte of the lithium-sulfurbattery contains an additive, therefore, interface state of a cathode, an anode and the separator is improved, charge-discharge current on the lithium anode surface is more uniform, activity of the lithium anode in the lithium anode can be reduced effectively, possibility of formation of lithium dendrites is reduced greatly, and use stability of the lithium anode is improved.