The present invention relates to a lithium-sulfur battery, a preparation method thereof and a positive electrode material. The binder comprises a polymer that is composed of a structural unit shown inthe formula (1) and a solution of carboxylic acid compounds with a polyalkenyl structure. The preparation method of the lithium-sulfur battery binder is also provided. The present invention also relates to the positive electrode material of the lithium-sulfur battery comprising the above lithium-sulfur battery binder. The technical solution of the invention binds polysulfide ions in the positiveelectrode and effectively suppresses the dissolution loss by providing the lithium-sulfur battery binder capable of reducing dissolution and shuttle of polysulfide ions, effectively adsorbs the polysulfide and improves the ion conduction efficiency. Meanwhile, preferable mechanical property is realized through the network cross-linking structure and the chemical interaction between sulfonic acid groups and polysulfide, and the effects of stabilizing the electrode structure and resisting the volume change during charge and discharge of the electrode are realized.