In this research, the impact of structural parameters of bipolar plates on the proton exchange membrane (PEM) fuel cell performance has been investigated using numerical method, and this model incorporates all the essential fundamental physical and electrochemical processes occurring in the membrane electrolyte, cathode catalyst layer, electrode backing, and flow channel, with some assumptions in each part. In formulation of this model, the cell is assumed to work under steady state conditions. Also, since the thickness of the cell is negligible compared to other dimensions, one-dimensional and isothermal approximations are used. The structural parameters considered in this paper are: the width of channels (Wc ), the width of support (Ws ), the number of gas channels (ng ), the height of channels (hc ), and the height of supports (hp ). The results show that structural parameters of bipolar plates have a great impact on outlet voltage in high current densities. Also, the number of gas channels, their surface area, the contacting area of bipolar plates, and electrodes have a great effect on the rate of reaction and consequently on outlet voltage. The model predictions have been compared with the existing experimental results available in the literature, and excellent agreement has been demonstrated between the model results and the experimental data for the cell polarization curve.