Inclusion Criteria:  Histologically confirmed, unresectable advanced or metastatic biliary tract cancer. Patients failed at least one prior line of systemic medications; if patients had disease progression during or within 6 months after the completion of adjuvant therapy or neoadjuvant therapy, the adjuvant therapy or neoadjuvant therapy could be regarded as one line of therapy. CLDN18.2 expression positive confirmed through tumor tissue. Patients with at least one measurable disease according to RECISTv1.1. ECOG PS of 0 or 1. Patients have predicted life expectancy ≥ 12 weeks. Paitients with adequate cardica, liver, renal function, etc.  Exclusion Criteria:  • History of another concurrent primary malignancy.  Untreated or symptomatic CNS metastases. Prior treatment targeting CLDN18.2. Major surgical procedure, prior locoregional therapy such as radioembolization within 28 days prior to the first dose of study drug. Prior serious hypersensitivity to monoclonal antibody or any component of the investigational drug. Patients had any of the following within 6 months prior to first dose of study treatment: cerebrovascular accident, transient ischemic attack, myocardial infarction or unstable angina pectoris, heart failure NYHA III or IV degree, or uncontolled uarrhythmia requiring intervention. Patients who are pregnant or lactating.