NOVELTY - Preparation of quaternized chitosan anion composite membrane comprises dissolving quaternized chitosan powder in 2 wt.% acetic acid solution; adding positively charged polystyrene emulsion to obtain membrane casting solution; stirring at room temperature for 4 hours; ultrasonically treating for 20-40 minutes; adding glutaraldehyde; stirring for 1 hour; ultrasonically treating for 30 minutes; pouring treated solution on flat glass plate; evaporating solvent to obtain composite film; and post-treating composite film.    USE - Preparation of quaternized chitosan anion composite membrane.    ADVANTAGE - The method provides composite membrane with high ion exchange amount and electric conductivity, and has low methanol penetration rate.    DETAILED DESCRIPTION - Preparation of quaternized chitosan anion composite membrane comprises adding styrene, absolute ethanol and deionized water to container at volume ratio of 1:5:10 to obtain mixed solution; adding (mass%) hexadecyl trimethyl ammonium bromide (0.5-5) and potassium persulfate (0.1-0.25) to mixed solution; reacting at 80 degrees C for 6 hours under protection of nitrogen gas to obtain positively charged polystyrene emulsion; cooling at room temperature; sealing and storing; adding chitosan and isopropanol to container at mass ratio of 1:4; heating in water bath while stirring; heating at 85 degrees C; adding aqueous solution of 50 wt.% 2,3-epoxypropyl trimethyl ammonium chloride, in which mass ratio of 2,3-epoxypropyl trimethyl ammonium chloride to chitosan is 1:1; stirring for 1 hour at constant temperature; vacuum distilling at 70 degrees C for 2 hours to remove deionized water and isopropanol; putting product in culture dish; baking at 80 degrees C for 40 minutes in oven; taking product out and shearing; baking at 80 degrees C for 5 hours in oven to obtain constant weight quaternized chitosan; crushing quaternized chitosan into powder; dissolving quaternized chitosan powder in 2 wt.% acetic acid solution; adding prepared positively charged polystyrene emulsion to obtain membrane casting solution, in which additional amount of polystyrene emulsion is 15-35 mass% of membrane casting solution; stirring membrane casting solution at room temperature for 4 hours; ultrasonically treating for 20-40 minutes; adding glutaraldehyde at 0.5 ml/minute and adding amount of 0.1-0.3 vol.% of membrane casting solution; stirring for 1 hour; ultrasonically treating for 30 minutes; pouring treated solution on flat glass plate; evaporating solvent at 40 degrees C to obtain composite membrane; placing composite membrane in 100 ml deionized water while changing water every 20 minutes; soaking for 3 hours; sweeping deionized water from surface of composite membrane; placing membrane at room temperature of 48 hours; slowly evaporating water; fixing composite membrane between Teflon (RTM: PTFE) plates; baking membrane in oven at 80 degrees C until it has constant weight; soaking dried composite membrane in 1.0 mol/l potassium hydroxide aqueous solution for 24 hours; performing ion exchanging; fixing composite membrane between Teflon (RTM: PTFE) plates; placing membrane in oven at 80 degrees C; and baking until membrane has constant weight.