Technological developments increasingly lead to equipment and products that are small and compact. Many technologies that use micro technology to support an efficient system. Two-phase flow (two-phase flow) is part of a multiphase flow that only involves two forms of a substance in a flow. In the study of the characteristics of two-phase flow in a mini pipe is very dependent on the surface tension that will affect the important parameters of the two-phase flow. This research was conducted in the test section in the form of a 1.6 mm diameter glass pipe with a length of 130 mm using a mixture of air-water and 3% butanol with a slope angle of 30⁰ to the horizontal position. The superficial velocity values of water and air are varied, namely JL = 0.033 - 4.93 m / s and JG = 0.025 - 66.3 m / s. In this study the mixture of water and butanol that has been mixed is flowed into a pressure vessel while the air is flowed using a compressor. Characteristic data of flow patterns and vacuum fractions are taken using a high speed camera with a speed of 1200 fps, while pressure drop data is obtained using a pressure transducer. In this study the flow patterns obtained are annular flow, bubble, churn, plug and annular slug. Comparisons obtained between the flow pattern maps of this study with the flow patterns maps of previous researchers have in common but there is a shift in the bubble and churn transition lines. The value of the vacuum fraction is influenced by the varied JG and JL and the flow patterns that occur. As for the pressure gradient results show that the gas superficial velocity (JG) and liquid superficial velocity (JL) greatly affect the pressure gradient value the higher the JG and JL values, the pressure gradient value will increase. The value of surface tension and the tilt angle affect the shape of the flow pattern and the pressure gradient value.