Abstract: A kinetic approach, named as the information preservation (IP) technique, is used to simulate rarefied gas flows in micro channels under conditions where experimental data are available with about several thousand microns of channel lengths and about 0.135 of the largest Knudsen number at the outlet. Some issues for IP calculation of the long micro channels such as the computational stability and convergence speed are addressed. The calculated stream wise pressure distributions and mass fluxes are in agreement with experimental data.