NOVELTY - A biomass-based anion exchange fiber preparing method involves drying a fruit of a loofah plant. A seed of the loofah fruit is peeled to obtain a cylindrical loofah sponge. The prepared sponge is activated and cleaned to obtain a processed dry vegetable sponge. The dry sponge is activated and heated to obtain a loofah sponge. The obtained loofah sponge is grafted to obtain a product that is added into pure hot water and stirred. The obtained cylindrical loofah sponge is cleaned followed by filtering till the filtrate is free from residues to obtain a biomass-based anion exchange fiber.    USE - Method for preparing a biomass-based anion exchange fiber.    ADVANTAGE - The method enables preparing a biomass-based anion exchange fiber with short time, low energy consumption, low preparation cost, good adsorption performance and recycling and regeneration function in simple and convenient manner.    DETAILED DESCRIPTION - A biomass-based anion exchange fiber preparing method involves naturally drying or drying a fruit of a loofah plant, and cutting into cylindroids. A seed of the loofah fruit is peeled from skin holes of the fruit to obtain a cylindrical loofah sponge. The prepared cylindrical loofah sponge is prearranged and activated for 5-10 hours in 5-20 wt.% sodium hydroxide water solution. The cylindrical loofah sponge is cleaned until neutral to obtain a processed dry vegetable sponge. 1-3 g dry sponge is activated with 80-120 ml N, N-dimethyl formamide and 20-80 ml mixed solution of epoxy chloropropane for 0.5-2 hours at 70-100 degrees C, and heated in a water bath and stirred followed by adding 5-10 ml ethylenediamine as a cross-linking agent and heating in the water bath at 70-100 degrees C for 0.5-2 hours, and adding 20-40 ml dimethylamine aqueous solution, and heating in the water bath at 70-100 degrees C for 2-4 hours to obtain a loofah sponge. The obtained loofah sponge is crosslinked and grafted to obtain a product that is added into pure hot water and stirred for 5 minutes. The obtained cylindrical loofah sponge is filtered and cleaned followed by repeating cleaning, filtering till the filtrate is free from residues to obtain a biomass-based anion exchange fiber.