【Abstract】 Objective To evaluate the feasibility and safety of EUS-MWA to liver and pancreas of pig through the observation of physiological state and pathological changes. Methods Microwave tissue coagulation of eight healthy pigs` liver and pancreas was performed through EUS-MWA with a microwave ablation needle of 1.9mm in diameter after general anesthesia. The power of liver ablation was set to 65W and time 10min; the counterpart of pancreatic ablation was set to 60W and time 5min. The blood amylase and hepatic transaminase were examined regularly after the operation. Pigs were all taken CT scan on the same day to assess the extent of ablation and complications. Four pigs were killed 6 hours and 24 hours after the operation to assess that is there any major structural damage around the puncture path. The remaining 4 pigs were raised to 2 weeks after the operation to observe the diet, activity and mental state. Pathological analysis of the ablated area of the liver and pancreas after dissection was performed, and the non-ablation region was treated as the control. Results All eight pigs tolerated the EUS-MWA of liver and pancreas well and vital signs were stable during operation. In addition to the difficulty of locating the pancreas in one case, other surgical procedures were smooth and sixteen ablations were performed totally (liver in 10, pancreatic in 8). On the same day, CT scans showed a quasi-circular low density lesion in the liver and pancreas (the maximum diameter of the liver and pancreas was 2.8±0.3cm, 2.0±0.2cm respectively) and there was no free intraperitoneal gas and ascites or pleural effusion. The level of blood amylase increased at 6h after the operation and the peak value occurred within 12-24h. The level of hepatic transaminase had a mild elevation. Rearing group after operation showed transient food refusal and activity reduction，but all began to gradually return to normal within 1-2 days after the operation. No fever, vomiting and other abnormalities was observed. No puncture path burn, adjacent organ damage and bleeding was observed except one case of gastric wall burns when ablated the pancreas. Pathological observation showed massive coagulative necrosis and peripheral bleeding area in the liver ablation center, and diffuse focal necrosis in the tissue of the pancreatic ablation area. Conclusion It is preliminarily confirmed that EUS-MWA is safe and feasible for liver and pancreas of pig. It is expected to be used for the treatment of human liver and pancreatic diseases in the future.