A 3D, single phase steady-state model has been developed for liquid feed direct methanol fuel cell. The model is implemented into the commercial computational fluid dynamics (CFD) software package FLUENT® v6.2, with its user-defined functions (UDFs). The continuity, momentum, and species conservation equations are coupled with electrochemical kinetics in the anode and cathode channel and MEA. For electro chemical kinetics, the Tafel equation is used at both the anode and cathode sides. Results are validated against DMFC experimental data with reasonable agreement and used to study the effects of cell temperature, channel depth, and channel width on polarization curve, power density and crossover rate. The results show that the increasing operational temperature, the limiting current density and peak of power density increase and subsequently crossover increases too. It is also shown that the increasing of channel width is a beneficial way for improving cell performance at a methanol concentration below 1 M.