In order to simulate and predict the complex mechanism of the high power CO laser excited by transverse dc discharge, a two-dimensional gas flow model has been developed from the authors' one-dimensional model. Based on the control volume method for two-dimensional Cartesian coordinates, the fundamental equations deal with state, continuity, momentum, energy, and reactions. The similar discharge power distribution can be given as the experiment, where the power density is higher around the hollow-cathode array than around the plane anode. Although the speed of the CO gas mixture is in the sub-sonic region, the effect of compression is taken into account. The integration is repeated by SIMPLEST method and the matrices are solved by MICCG method for the pressure equation and by MILUCR method for the other equations. The computation is carried out by a HITAC S820 supercomputer and a Sun-4 workstation. As a result of the simulation, non-uniform distribution of the gas parameters was made clear.