Pt/CNTs were synthesized with an ethylene glycol reduction method, and the effects of carboxyl functionalization, ultrasonic power and the concentration of chloroplatinic acid on the catalytic activity of Pt/CNTs were investigated. The optimal performance of the Pt/CNTs catalyst was obtained when the ultrasonic power was 300 W and the concentration of chloroplatinic acid was 40 mg/mL. The durability and stability of the Pt/CNTs catalyst were considerably better compared to Pt/C, as shown by cyclic voltammetry measurement results. The trans fatty acids content of the obtained hydrogenated soybean oil (IV: 108.4 gl2/100 g oil) using Pt/CNTs as the cathode catalyst in a solid polymer electrolyte reactor was only 1.49%. The IV of hydrogenated soybean oil obtained using CNTs as carrier with Pt loading 0.1 mg/cm2 (IV: 108.4 gl2/100 g oil) was lower than carbon with a Pt loading of 0.8 mg/cm2 (IV: 109.9 gl2/100 g oil). Thus, to achive the same IV, the usage of Pt was much less when carbon nanotubes were selected as catalyst carrier compared to traditional carbon carrier. The changes of fatty acid components and the hydrogenated selectivity of octadecenoic acid were also discussed.