Objective To compare temperature curve and ablation zone between 915 MHz and 2450 MHz cooled shaft microwave antenna in ex vivo porcine livers.Methods The 915 MHz and 2450 MHz microwave ablation and thermal monitor system were used in this study.A total of 56 ablation zones and 280 temperature data were obtained in ex vivo porcine livers.The output powers were 50,60,70,and 80W and the setting time was 600s.The temperature curve of every temperature spot,the short- and long-axis diameters of the coagulation zones were recorded and measured.Results At all four power output settings,the peak temperatures of every temperature spot had a tendency to increase accordingly as the output power was increased,and except for 5 mm away from the antenna,the peak temperatures for the 915 MHz cooledshaft antenna were significantly higher than those for the 2450 MHz cooled-shaft antenna (P ＜0.05).Meanwhile,the short- and long-axis diameters for the 915 MHz cooled-shaft antenna were significantly larger than those for the 2450 MHz cooled-shaft antenna ( P ＜0.05).Conclusions The 915 MHz cooledshaft antenna can yield a significantly larger ablation zone and achieve higher temperature in ablation zone than 2450 MHz cooled-shaft antenna in ex vivo porcine livers.