Graphene has attracted great interest for its distinctive band structure and physical properties. Results from previous studies show that a graphene cathode can provide stable field emission and intense emission in vacuum. This paper presents two metal matrix graphene film cathodes prepared by different methods. One is a copper/graphene matrix cathode grown by chemical vapor deposition, the other is a stainless steel/graphene matrix cathode transferred by substrate corrosion. The surface morphology of the graphene films on these two cathodes was examined using a scanning electron microscope (SEM) and Raman spectroscopy. The thickness and uniformity of the graphene film was evaluated. Gas spark switches based on these two cathodes were developed. The impulse-breakdown characteristics of these switches in a quasi-uniform electric field were studied. When the gap length is 5 mm and the gas pressure is 0.6 MPa, the average breakdown voltage (U_BD) for copper/graphene matrix cathode is nearly 85.9 kV, and the voltage jitter is 3.2%; the average U_BD for stainless steel/graphene matrix cathode is nearly 59.8 kV, and the voltage jitter is 2.4%. According to preliminary analysis, the surface state of the cathode and the quality of the graphene film directly affect the breakdown stability of the gas switch.