The invention provides a preparation method for a fluorine-doped three-dimensional structured positive electrode material of a lithium-sulfur battery. The preparation method comprises the following steps of (1), adding graphite oxide into water for performing ultrasonic processing to form a graphene oxide suspension liquid; (2), adding tetrabutylammonium fluoride to the graphene oxide suspension liquid, then transferring to a hydrothermal kettle to perform a hydrothermal reaction, after the reaction is completed, performing ethyl alcohol washing, water washing, freezing and drying to obtain three-dimensional fluorine-doped graphene; (3), adding the obtained three-dimensional fluorine-doped graphene and ketjen black into N-methyl pyrrolidone for performing an ultrasonic reaction to form a suspension liquid; (4), adding elemental sulfur to the N-methyl pyrrolidone for performing an ultrasonic reaction until the elemental sulfur is fully dissolved to form a suspension liquid; and (5), mixing the obtained two kinds of suspension liquid, uniformly stirring, slowly adding distilled water while stirring, and then performing centrifuging, water washing, and drying to obtain the three-dimensional structured positive electrode material of the lithium-sulfur battery. Due to the preparation method, the cycling life of the lithium-sulfur battery is prolonged.