The purpose of this study is to evaluate the efficacy and safety of EUS-BD compared with ERCP-BD in low biliary obstruction caused by periampullary cancer, pancreatic cancer or low bile duct cancer. This is a single center, prospective, randomized-controlled study. The primary endpoint of this study is stent patency time, and secondary endpoints include technical success rate, clinical success rate, operation time, operation related complications rate, reintervention rate, stent patency rate at 6 months, and 1-year postoperative survival rate.

Inclusion Criteria:

1. Age:18 years old or above;
2. Periampullary cancer/pancreatic cancer according to pathology or clinical judgment of more than 2 senior doctors;
3. Distal malignant bile duct obstruction (2cm away from the hepatic hilum);
4. Ultrasound evaluation shows that the accessible part of the bile duct has a width of ≥ 12mm;
5. The patient or family member is able to understand the research protocol and is willing to participate in this study, providing written informed consent.

Exclusion Criteria:

1. Patients suffer from severe cardiovascular or pulmonary diseases who are unable to tolerate anesthesia or endoscopic examination;
2. Uncorrectable coagulation abnormalities or bleeding tendencies (INR>1.5 or platelets<50) × 109 /L);
3. There is a plan for subsequent surgical resection of the tumor, accompanied by severe infection or an expected survival period of less than 3 months;
4. Successful biliary drainage measures have been implemented, including but not limited to ERCP, ENBD, PTCD, and surgical procedures;
5. Previous surgical changes to the anatomical structure of the pancreas, gallbladder, stomach, and duodenum;
6. Pregnancy, lactation, or planned pregnancy;
7. Refusal to join or inability to provide informed consent;
8. Other researchers evaluated the unsuitability of enrollment.