Objective　The micro-arterial cast specimens of extrahepatic bile duct were used to elucidate the source and distribution of extrahepatic bile duct blood supply and the characteristics of multiple annular vascular networks between the anastomosis artery chains of the upper duodenal bile duct, providing a clinical anatomical basis for biliary surgery.　Methods　Six cases of extrahepatic bile duct arteries were injected with acrylic resin as arterial filler. Photoshop was used to measure the inner diameter of small blood vessels. The blood supply source and distribution of extrahepatic bile duct were observed and analyzed.  Results  The left and right branches of the proper hepatic artery had arcuate communicating branches above the hepatic duct. There were abundant transverse arteries between the anastomotic artery chains at the left and right edges of the upper duodenal bile duct. The blood supply of anastomotic arterial chain was about 53% from the bottom, 46% from the top and 1% from the middle hepatic artery. Through the measurement of the diameter of the middle segment of each transverse artery and the initial diameter of both sides, it was found that the middle and upper segments of the  transverse arteries of the hepatic duct were larger, with an average middle diameter of （0.26±0.02）mm and（0.24±0.04）mm, respectively. The ratio of inner diameter of the upper segment to the middle segment was 1.09. The ratio of the middle segment to the middle segment was 1. The average inner diameter of the middle part of the lower segment was（0.14±0.03）mm. The ratio of inner diameter to both sides was 0.74.　Conclusions　The blood supply at the upper and lower ends is relatively balanced. In order to alleviate the injury of extrahepatic bile duct blood supply, a small longitudinal incision should be made in the upper part of the duodenum of the common bile duct and the lower part of the small common hepatic duct with less arterial anastomosis as far as possible. The blood supply of the common hepatic duct is abundant, supporting the current proposition that the isolated site of orthotopic liver transplantation is above the confluence of the gallbladder.