Inclusion Criteria:  18 to 75 years old. Have a life expectancy of at least 3 months. Have an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. Phase Ib:Histologically or cytologically confirmed advanced solid tumor.  Phase II:  cohort 1 : Has histologically confirmed diagnosis of unresectable locally advanced,recurrent or metastatic gastric or GEJ adenocarcinoma.  cohort 2 : Has histologically confirmed diagnosis of unresectable locally advanced,recurrent or metastatic Biliary Tract Cancers, including intrahepatic cholangiocarcinoma, extrahepatic bile duct cancer, gallbladder cancer.  cohort 3 : Has histologically confirmed diagnosis of unresectable locally advanced,recurrent or metastatic pancreatic ductal adenocarcinoma.  Have at least one measurable lesion based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 assessed by investigator. Has adequate organ function.  Exclusion Criteria:  Undergone major surgery within 30 days prior to the first dose of study treatment. Active central nervous system (CNS) metastases. History of active autoimmune disease that has required systemic treatment in the past 2 years (i.e.,corticosteroids or immunosuppressive drugs). Active Hepatitis B or Hepatitis C. Received previous immunotherapy, including immune checkpoint inhibitors, immune checkpoint agonists, immune cell therapy and other treatments targeting the mechanism of tumor immunity. History of severe bleeding tendency or coagulation disorder.