Objective To discuss the precise operational skill of Kasai operation in biliary atresia, in order to increase postoperative jaundice-free rate and improve prognosis. Methods The clinical data of 189 cases of type Ⅲ biliary atresia were analyzed admitted into Department of General Surgery, Beijing Children's Hospital, Capital Medical University, from Jul.2002 to Dec.2012 retrospectively, 117 male and 72 female(1.63∶1.00). Age at Kasai procedure ranged from 34 days to 110 days, with mean age 76 days.All of the 189 cases restored bile drainage after Kasai operation; during operation dissect the cone-shaped fibrous tissue at porta hepatis with needle-shaped electrotome, then cut off impotent extrahepatic biliary tract and fibrous tissue at porta hepatis with tissue scissor, and a Roux-en-Y loop of jejunum was anastomosed around the fibrous edges of the transected tissue, forming a portoenterostomy.The key skills which to guarantee good bile drainage during operation: (1)Use needle-shaped electrotome to dissect fibrous tissue at porta hepatis in order to obtain precise dissection, less blood loss and minimal invasion.(2)Stop the blood flow of the 4-6 small venous branches below the fibrous tissue at porta hepatis which return to portal vein with electrocoagulation, in order to dissect the cone-shaped fibrous tissue until above the level of portal vein branches.(3) Cut off the fibrous tissue at porta hepatis with tissue scissor, then press the transsection to stop bleeding, with local application of 1∶100 000 adrenalin if necessary.(4) Prepare sutures with needles at the dorsal edge of transsection previously, then anastomose the ventral edge, which would make portoenterostomy less difficult and more precise.(5) In order to reduce the chance of postoperative cholangitis, the jejunal Roux-en-Y loop should better be more than 60 cm, and antireflux valve should be done. Results All of the 189 cases achieved cholic stool soon after operation, 56.7% patients achieved jaundice-free 6 months after operation(total bilirubin <20 μmol/L). Conclusion Precise procedure of Kasai operation is the key guaranty of good prognosis for biliary atresia patients. Key words: Biliary atresia; Kasai operation; Prognosis