Computational simulation model has been used extensively, in studying the filling flow in injection molding process. Most of the models are based oil the assumption of a no-slip boundary condition and are verified by; the experiments of filing flow in macro scale. This study is to investigate the flow behaviors during the micro channel filling of an injection molding process. Flow distances were measured oil products from series of short shots to understand the relationship between the injection pressure and flow distance. It was found that cavity, size variation due to mold deformation is important in the micro injection molding. By, adjusting the cavity, size due to mold deformation, the C-Mold simulation provides reasonable results compared to the experimental data for cavity thickness in 150 mu m or 200 mu m. Oil the other hand, the simulation will not give accurate prediction of filling flow for a micro cavity, that has a depth below 100 mu m. The wall slip effect is believed to the major reason and must be considered in the analysis for a cavity size below 100 mu m.