Carbon nanotubes have excellent mechanical and electrical properties such as high stiffness, light weight, heat stability, excellent heat conductivity, and excellent electrical conductivity. This study was aimed into investigate the properties of composites consisting of adding several different proportions of carbon nanotubes to phenolic resin, which contained tensile strength, fatigue life and electrical properties. The experimental results showed that the electric resistance decreases as the weight percentage of the nanotubes increases, also the tensile strength increased as the nanotubes increased. After the different moisture-temperature circumstances and thermal cycling, the increase of the electric resistance was compared to the pristine composites. The experimental results hoped to be understood from the fracture surface observations by scanning electron microscope (SEM).