Abstract: To study the effect of the vessel on the ablation field, the temperature field near the blood vessel at different distances from the antenna and different blood flow rates were measured in vitro experiments. Using infusion tube instead of hepatic lartery, and setting the flow rate based on the blood flow velocity of the hepatic artery, copper-constantan thermocouples (TCs) were used to measure the temperature near the blood vessel in vitro experiments, which were compared with the simulation results in the same condition. Experimental results showed that when the microwave antenna was 1.0 cm away from the vessel, the heating pattern was not symmetrical about the antenna because the heat convective of blood, and large temperature gradient existed in the side of the blood vessel. The greater the blood flow was, the smaller the temperature field of microwave ablation was. When the antenna was 1.5 cm away from the blood vessel, the heating pattern was more circular, and the temperature contours of two blood flows were almost overlapped. When the antenna was 2.0 cm away from the blood vessel, the heatingpattern was circle, and almost symmetrical about the microwave antenna. When the blood flow increased (from 22 cm/s to 55 cm/s) , vessel influence on the temperature field increased (the temperature difference with 22 cm/s up to 10 ℃) , and temperature fields further reduced. The effect of blood on the temperature field could be ignored if the distance between blood vessel and the microwave antenna exceeded 2.0 cm. When the distance was less than 2.0 cm and the blood velocity was more than 22 cm/s, in order not to affect the efficacy of the ablation, blood vessel blocking was suggested to implement.