The invention relates to a method for preparing a catalytic/gel dual-functional composite separator for a lithium sulfur battery by an electrostatic spinning technology. The composite lithium sulfur battery separator is characterized by being formed by combining a layer of antimony tin oxide-doped aramid film with a thickness being 25-30 micrometers and a layer of fluorine-doped aramid film with athickness being 45-50 micrometers. The catalytic/gel dual-layer aramid composite separator is prepared by an electrostatic spinning technology. The preparation method of the catalytic/gel dual-functional composite separator for the lithium sulfur battery comprises the following steps of 1) preparing the antimony tin oxide-doped aramid film by an electrostatic spinning method; 2) preparing a fluorine-doped aramid nanofiber film by an electrostatic spinning technology, and preparaing an antimony tin oxide-doped aramid/fluorine-doped aramid nanofiber composite film in an on-line combination way;and 3) placing the prepared dual-layer composite aramid nanofiber film in a vacuum baking oven for drying, and performing hot pressing. The process is simple, the production cost is low, the preparedcatalytic/gel dual-functional composite separator for the lithium sulfur battery has favorable liquid lyophilicity, excellent thermal stability and excellent mechanical property and is beneficial forimproving the ion conductivity of the separator and improving the cycle stability of the battery.