The utility model relates to a device of preparing a flexible graphite water flow field used for a proton exchange film fuel battery, which is characterized in that the flexible graphite water flow field is prepared by adopting a stamping mode, a stamping die is provided with a punching knife edge die which is designed according to a flow field graph, a plane of a knife edge die is provided with an elastic material plate which is level with a knife edge or is a little higher than the knife edge, and a stamping baffle die is provided with a hard nonmetallic material bottom plate, therefore, the defects of low production efficiency, poor repeatability and unsmooth edge of hand engraving in preparation of the flexible graphite water flow field are completely overcome, the preparation efficiency of the flexible graphite water flow field can be greatly enhanced, the production efficiency can be enhanced at least by more than 1.5 times compared with the existing hand production, the device is easier to produce the water flow field in a large scale, and the consistency of punching flow field is favorable and can achieve repeat near 100 percent; and in addition, the edge of the punched flow field is smooth, and the water flow is enhanced.