Numerical simulation is carried out to investigate the flow characteristics of two-dimensional laminar incompressible slot jet flows. Simulations are done for a vertical slot jet on a block at the bottom wall, and the top wall is confined by the parallel surface. The reattachment length, detachment length, vortex center and the coefficient of friction (C _f) are analyzed for different types of flow patterns. The correlation between the Reynolds number (Re) with vortex center and reattachment length is recommended. A detailed study is reported on the horizontal velocity profiles at various downstream locations by varying the aspect ratio (AR) (2 ≤ AR ≤ 5), block width (0.25 ≤ w/D _h ≤ 1.75), block height (0.25 ≤ h/D _h ≤ 1.0) and the jet exit Reynolds numbers (100 ≤ Re ≤ 300). The critical Reynolds number for the formation of the secondary vortex is obtained. The numerical results indicated that the C _f value increases while decreasing the distance between the jet and the impingement block. It is found that the effects of AR and Re are more influencing on the fluid flow field, compared to the block width and the block height.