Surface tension of polymer fulid breaks thin layer of polymer fluid to approach thermally equillibrium state which can minimize surface energy. This pheneomena is called as a "De-wetting". Previously, de-wetting pheneomana of polymer have been investigated in many ways such as interaction between surface chemistry, polymer chain formation of block copolymer and surface topology, etc. However, PS has been widely used for the pattern transfer layer for various lithographic techniques. Especially for the soft lithography, de-wetting behavior of polymer fluid has an important role to define the resulted feature. In this study, we focused on de-wetting phenomena of Polystyrene(PS), especially the effect of molecular weight, and observe how PS fluid trasform their feature under specific physical confinement made by PDMS(polydimethylsiloxane), the profile of the final patterns were investigated in detail.