Abstract: The interfacial tensions of binary liquid-liquid systems ( n-heptane+water), ( n-hexane+water) , (n-octane+water) , (n-nonane + water), (n-heptanol water) , (n-hexanol+water) , (n-octanol+water) , (n- nonanol + water) in the temperature range from 298.15 K to 343.15 K at constant pressure were measured by the pendant drop method. The interfacial tensions of aliphatic hydrocarbon - water systems decreased linearly with higher temperature, but those of aliphatic alcohol - water systems increased, then decreased with higher temperature. In addition, the N - A method used for estimating interfacial tensions was discussed further, which is paid a good deal of attentionto and is one of the purposes of this research.