NOVELTY - Preparing water retaining type proton exchange membrane for fuel cell comprises coating the perfluosulfonic resin solution on the surface of the expanded polyfluortetraethylene micropore membrane.    USE - The methods are useful for preparing water retaining type proton exchange membrane for fuel cell (claimed).    ADVANTAGE - The water retaining component of the silica is distributed according to the gradient method, it can guarantee the absorptive capability for the water and reduce the total resistance of the composite proton exchange membrane; it has the water retaining function; it can reduce the dependency of the humidification system for the proton exchange membrane fuel cell; it can guarantee the normal work of the composite proton exchange membrane at the low-humidifying environment; it is easy to realize the large-scale production; the thickness is even, the wet strength is high; and the dimension stability is good.    DETAILED DESCRIPTION - Preparing water retaining type proton exchange membrane for fuel cell comprises coating the perfluosulfonic resin solution on the surface of the expanded polyfluortetraethylene micropore membrane; the preparation method of water retaining type proton exchange membrane comprises: (a) preparing the solution I: adding certain amount of high boiling point solvent and silica in the perfluosulfonic resin solution of 0.1%-4.5% mass concentration; having the ultrasonic vibration process; the mass ratio of the high boiling point solvent and perfluosulfonic resin is 1:1-8:1; the silica is added in the mode of silica sol or powder; the mass ratio of the silica and perfluosulfonic resin is 0:1-0.15:1; the solvent system of the perfluosulfonic resin solution is comprised of the alcohol and water; the alcohol in the solvent system of the perfluosulfonic resin solution comprises the methanol, ethanol, n-propanol, isopropanol, n-butanol; the high boiling point solvent is any one of the N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone; (b) preparing the solution II: adding certain amount of high boiling point solvent and silica in the perfluosulfonic resin solution of 5%-20% mass concentration; having the ultrasonic vibration process; the mass ratio of the high boiling point solvent and perfluosulfonic resin is 1:1-8:1; the mass ratio of the silica and perfluosulfonic resin is 0:1-0.15:1; the silica is added in the mode of silica sol or powder; the solvent system of the perfluosulfonic resin solution is comprised of the alcohol and water; the alcohol in the solvent system of the perfluosulfonic resin solution comprises the methanol, ethanol, n-propanol, isopropanol, n-butanol; the high boiling point solvent is any one of the N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone; (c) preparing the solution III: adding certain amount of high boiling point solvent and silica in the perfluosulfonic resin solution of 5%-20% mass concentration; having the ultrasonic vibration process; the mass ratio of the high boiling point solvent and perfluosulfonic resin is 0.5:1-10:1 and the mass ratio of the two parts, the mass ratio of the high boiling point solvent and perfluosulfonic resin is higher than the mass ratio of the high boiling point solvent and perfluosulfonic resin in the solution II for 0.5-2; the mass ratio of the silica and perfluosulfonic resin is 0.01:1-0.10:1; the silica is added in the mode of silica sol or powder; the solvent system of the perfluosulfonic resin solution is comprised of the alcohol and water; the alcohol in the solvent system of the perfluosulfonic resin solution comprises the methanol, ethanol, n-propanol, isopropanol, n-butanol; the high boiling point solvent is any one of the N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone; (d) preparing the solution IV: adding certain amount of high boiling point solvent and silica in the perfluosulfonic resin solution of 5%-20% mass concentration; having the ultrasonic vibration process; the mass ratio of the high boiling point solvent and perfluosulfonic resin is 0.5:1-10:1, the mass ratio of the silica and perfluosulfonic resin is 0.03:1-0.2:1, and the mass ratio of the two parts is that the mass ratio of the silica and perfluosulfonic resin is higher than the mass ratio of the silica and perfluosulfonic resin in the solution III for 0.02-0.1 while preparing concretely; the silica is added in the mode of silica sol or powder; the solvent system of the perfluosulfonic resin solution is comprised of the alcohol and water; the alcohol in the solvent system of the perfluosulfonic resin solution comprises the methanol, ethanol, n-propanol, isopropanol, n-butanol; the high boiling point solvent is any one of the N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1-methyl-2-pyrrolidone; (e) fixing the expanded polyfluortetraethylene micropore membrane on the support frame with opposite size; the support frame fixed with the expanded polyfluortetraethylene micropore membrane is the membrane frame; locating the membrane frame into the solution I prepared in step (a), having the infiltration process for 10-60 minutes; (f) taking out the membrane frame dipped in the solution I prepared in step (a), removing the solution on the surface of the membrane frame, locating the membrane frame into the solution II prepared in step (b), having the infiltration process for 10-60 minutes; (g) taking out the membrane frame dipped in the solution II prepared in step (b), removing the solution on the surface of the membrane frame, locating the membrane frame on the hot table of 60-150 degrees C and drying; (h) coating the solution III prepared in step (c) at two side surfaces of the membrane frame processed by the solution prepared in step (a) and step (b) and coating again and again until that the thickness is the requirement thickness; (i) locating the membrane frame coated in step (h) on the hot table of 60-150 degrees C and drying; (j) using the solution IV prepared in step (d) for coating the two side surfaces of the membrane frame processed in step (i) and coating again and again until that the thickness is the requirement thickness; and (k) locating the membrane frame processed in step (j) in the oven, drying at 120-220 degrees C, the drying time is 0.5-8 hours, so the integrated water retaining type proton exchange membrane can be prepared.