The research on the liquid flow at micro-scale is of great significance to develop low permeability oil/gas reservoirs at high efficiency. In this paper, the flow characteristics of de-ionized water andn-Hexadecane flowing through quartz microtubes with inner diameter of 18.5 μm, 9.6 μm and 4.1μm were investigated in experiments. The experimental results show that the pressure drop has linear relationship with average velocity of the fluid in the microtubes. The experimental friction factor is consistent with the classical laminar flow theory when the flow velocity ranges in 0.01 mm/s -1 mm/s, which indicates that the influence of the stationary boundary layer could be neglected when the diameter of the microtube exceeds 4 μm. The nonlinear Darcy phenomenon that the flow resistance increases as the reduction of flow rate and the obvious phenomenon of the starting pressure do not occur for the Newton fluid flow in microtubes.