In this work, carbon fiber carrying platinum-nickel alloy is used as a sensing electrode material to develop a H2S gas sensor based on Nafion proton membrane. Characterizations of the material by X-ray diffraction (XRD), scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS) reveal that the structure and morphology of the particles change with the ratio of the alloy. The electrochemical specific area (ECSA) of the material is calculated by cyclic voltammetry, which further proves the influence of alloy formation on the catalytic performance of the materials. When the ratio of platinum to nickel is 1:1, the material is uniformly loaded and its catalytic performance is optimal. Thus, the device made with it has the highest sensitivity. The sensor's low detection limit is 0.2 ppm. For the incorporation of nickel, the sensitivity is increased to -0.306 mu A/ppm, which is 18 % higher than before. Not only does the sensor have good repeatability and short response recovery time, the presence of oxygen and water vapor does not have much effect on the sensor. Therefore, it has a great application potential in the field of gas detection at room temperature.