Abstract: The plasma flow field of solid target in atmosphere under impulse laser irradiation was computed. The flow is governed by the 2-D Reynolds averaged Navier-Stokes (NS) equations. The k-ε turbulence model was used for turbulence simulations. To split the viscosity flux and the convective flux of the NS equations, the second order central scheme and the ROE scheme were adopted respectively. With the implicit Gauss-Seidel scheme, the code was advanced in time. The 2-D hydrokinetics process of laser plasma was presented in this paper by numerical simulation. The influence of target dimension and laser spot size on laser impulse was discussed. The results indicated that laser impulse increases generally with target dimension.