A one-dimensional, two-phase, steady-state, multi-component transport as well as electrochemistry behavior mathematic model of a PEM fuel cell cathode is presented in this study. The catalyst layer structure is considered to be a cylindrical thin-film agglomerate. The objective of the study is to investigate the effects of the cell performance under different design parameters, such as platinum loading, radius of catalyst pellet, Nafion film thickness, catalyst layer thickness, and porosity of catalyst layer. Results of this model was agreed reasonably with the numerical modeling and experimental data of Lin et al. In addition, the electrochemical transport phenomena, such as oxygen concentration, water concentration, water saturated, and ionic potential, were examined. The parametric analysis reveals the important role of transport mechanism in catalyst layer and our results provides useful information on the electrode design parameters of PEM fuel cells for the MEA manufacturer.