The lifetime of a PEM fuel cell depends strongly on the local current distribution on the electrode. Uneven distribution of local current on the electrode means irregularity of the electrochemical reaction on the reacting site. It not only reduces the cell performance but also shortens its lifetime. The local current distribution on a PEM fuel cell will be affected by many factors, such as cell temperature, degree of humidification, partial pressure of the feeding gases, configuration of the flow channels, microstructures and characteristics of the electrodes, etc. Therefore, it is very important to understand the above effects on local current distribution for designing and operating a PEM fuel cell. In the present work, a novel fixture is designed to in-situ map the local current distribution on the electrode of a PEM fuel cell. An array of 4 by 4 segmental current collectors is distributed on the cathodic flow-field plate. Each conductive segment is insulated mutually. Current through each current collector is measured individually by using a Hall-effect sensor, which well represents the regionally averaged data on its counterpart. A self-made MEA is integrated into the above single-cell fixture for local current measurement. Parametric studies include the cathodic flow-field patterns, the cathodic-feeding stoichiometries, and the dew point of cathodic feedings. The influences of flow-field pattern and stoichiometry variation of feeding gases are discussed in terms of the measured local current distribution of in the segmented single cell.