A method for preparing an alkaline anion exchange membrane based on a branched oxygen-free main chain belongs to the field of battery membrane materials. The method comprises: firstly, dissolving 1,3,5-triphenylbenzene, N-methylpiperidone, biphenyl and trifluoroacetone in a solvent, adding an catalyst under an ice bath condition, and obtaining a polymer main chain having a branching degree of 1 to5 after a reaction; secondly, dissolving and reacting N-methylpiperidine and 1,6-dibromohexane in ethyl acetate, and then processing an obtained product ionization reagent; finally, performing the ionization of the polymer membrane main chain, casting membrane, and alkali treatment to obtain an anion exchange membrane. The method reduces the risk that hydroxide attacks the membrane by using the oxygen-free main chain, thereby enhancing the alkali resistance of the anion exchange membrane. The branched structure provides a certain free volume to help build ion transmission channels, and the ion reagent can promote the formation of ion clusters as well as the separation of hydrophilic and hydrophobic microphases, thereby significantly improving the conductivity of the membrane.