Visual micro-model technology has been applied to investigate multiphase flow in porous media because it allows watching the fluid flow clearly with a microscope. However, most micro-models employed are made up of glass media. A sandstone micro-model (SMM) manufactured directly from thin sandstone chips is introduced and applied in this study of water injection in low permeable rock. The main advantage for this kind of micro-model is that it retains the original pore structure, clays, cements, and pore surface properties. A total of 18 sandstone micro-models with permeability from 1 - 10 md are used for displacement tests at room temperature. Results show that the water injection in the weakly oil-wet to neutral-wet low permeable sandstone micro-model is dominated by the injection pressure. At low injection pressure, the water can only enter large pores that have good conductivity. A large number of pores are not flooded by water. When the injection pressure is increased, water is forced into some small pores to drive oil out. In addition, heterogeneous properties of the porous media always cause a bypass flow resulting in early water breakthrough and poor water displacement efficiency. We also found that oil recovery is directly proportional to the permeability of the model, suggesting that pore conductivity is the key to waterflood efficiency in low permeable rock.