Abstract: Proton exchange membrane fuel cell(PEMFC) has the advantages of high specific energy, clean and efficient. As one of the core structures of PEMFC, the structure size of channel has an important impact on the gas transmission and liquid water removal. Selecting appropriate size parameters is of great significance for practical operation.Taking 50 mm×50 mm single serpentine channel cell as the research object, a three-dimensional two-phase isothermal model of PEMFC was established by numerical simulation. The effects of channel depth, channel width and channel ridge width on cell current density, gas mass transfer characteristics, net output power and drainage performance were analyzed. Results show that with the decrease of channel depth and channel width, the oxygen concentration involved in the reaction increases, the current density increases, the net output power increases, the drainage performance of the catalytic layer improves, and the cell performance improves gradually. With the decrease of the ridge width of the channel, the oxygen concentration participating in the reaction gradually increases, and the current density increases, however, the increase of the net output power in the channel is comparatively small, and the increase of the oxygen concentration is comparatively slow.