Clinically, according to the invasion of hepatic artery and portal vein, the course of cholangiocarcinoma can be divided into 4 stages: Stage I: tumor is limited to bile duct without portal vein and hepatic artery invasion; Stage II: tumor involves portal vein and hepatic artery unilaterally; Stage IIIa: tumor involves one side of hepatic artery and bifurcation of portal vein; Stage IIIb: tumor involves one side of portal vein and hepatic artery; Stage IV: tumor involves hepatic artery and bifurcation of portal vein.