A method for carbonizing the gas diffusion layer of the proton exchanging membrane fuel cell is provided, which relates to a preparation method for gas diffusion layer of the proton exchanging membrane fuel cell. The invention overcomes the shortcomings of the block for gas mass transfer caused by high PTFE capacity and the electrical conductivity decreasing of carbon paper electron. The approach of the invention is as follows: first, immersing the carbon paper in 10 to 50 wt. % aqueous solution of carbohydrate or hydrocarbon polymer for 30 to 80 min, drying the carbon paper up for 20 to 24 hours under the condition of 50 to 80 degrees centigrade, sintering the paper for 30 to 60 minutes in tubular furnace with the temperature of 350 to 400 degrees centigrade and under the protection of Ar gas; second, repeat the first operation step; third, immersing the carbonized carbon paper in 5 to 20wt. percent emulsion of Polytetrafluoethylene for 10 to 30 minutes. Thus the gas diffusion layer of carbon paper carbonized modification proton exchanging membrane fuel cell is obtained. The Polytetrafluoethylene capacity of the product in the invention is 10 to 20wt. percent . The invention has the advantage of improving the electrical conductivity of cell gas diffusion layer and porosity factor.