Inclusion Criteria:  Phase Ia and Ib: Aged 18 to 65 years old male and female; Phase IIa :Aged 18 to 75 years old male and female Phase I study: Phase Ia and Phase Ib will enroll patients with HER2-positive advanced solid tumors who were confirmed by histopathology and/or cytology and who had failed standard treatments. Phase IIa study: Cohort 1 will enroll patients with HER2-positive advanced biliary system tumors who were confirmed by histopathology and/or cytology and failed standard treatment. Cohort 2 will enroll patients with newly treated HER2-positive advanced biliary system tumors diagnosed by histopathology and/or cytology. According to the RECIST 1.1 standard, at least one measurable lesion exists, and the measurable lesion has not received local treatment (including local radiotherapy, ablation, and interventional therapy). ECOG performance status 0-1. Laboratory examination should meet: ① Blood routine: hemoglobin (HGB) ≥100 g/L, white blood cell count (WBC) ≥3.0×10^9/L, neutrophil count (ANC) ≥1.5×10^9/L, platelet count ( PLT) ≥75×10^9/L; ②Blood biochemistry: total bilirubin (TBIL) ≤1.5×upper limit of normal (ULN), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤3.0×ULN, serum creatinine ( Cr)≤1.5×ULN or calculate the creatinine clearance ≥50 mL/min according to the Cockcroft-Gault formula method. Left ventricular ejection fraction (LVEF) ≥ 50% by echocardiography. Life expectancy ≥3 months. Agree to use at least one medically approved contraceptive method during the trial period and at least 6 months after the last dose (female patients: such as intrauterine devices, contraceptives or condoms, etc.; male patients: such as condoms, abstinence, etc.). Female patients must be non-lactating. Subjects must be fully informed of the content, process and possible risks and benefits of the research and sign the informed consent form. Good compliance, able to complete the study and follow-up.  Exclusion Criteria:  Known to have hypersensitivity to any monoclonal antibody. Not recovered from the adverse reactions caused by previous anti-tumor treatments (refer to CTCAE 5.0 to judge, hematological toxicity ≥ 2 grade, non-hematological toxicity ≥ 1 grade). Long-term toxicity after radiotherapy, which is judged to be irreversible by researchers, such as hair loss and pigmentation are excluded. Previously received allogeneic hematopoietic stem cell transplantation or solid organ transplantation. Have undergone surgery within 4 weeks before enrollment, and the investigator believes that the patient's state has not recovered to the point where the study can be started. Received a preventive vaccine or attenuated vaccine or have received blood transfusion within 4 weeks before joining the group. Stage Ia and Stage Ib: Patients who have received trastuzumab and its biosimilar drugs (including single drugs, combination chemotherapy, ADC drugs, bispecific antibodies, etc.) 6 months before enrollment. Stage IIa: Patients who have previously received anti-HER2 therapy. Have received any systemic anti-tumor therapy within 4 weeks before enrollment. Participated in other clinical trials within 4 weeks before enrollment and used clinical research drugs during this period. Central nervous system metastases with clinical symptoms were found within 4 weeks before enrollment. Patients who have previously received treatment for brain or meningeal metastases, if clinical stability has been maintained for at least 2 months, and have stopped systemic hormone therapy (dose>10 mg/day prednisone or other curative hormones) for more than 4 weeks can be included. Patients with ascites (ascites), pleural effusion (pleural effusion) or pericardial effusion that cannot be controlled by drainage or other methods. Past or present suffering from other malignant tumors (except for cured skin basal cell carcinoma and cervical carcinoma in situ). Suffer from serious or poorly controlled diseases, including but not limited to: ① Myocardial infarction, unstable angina pectoris, clinically significant arrhythmias requiring treatment, congestive heart failure, pericarditis, myocarditis, etc. occurred within 6 months before enrollment. ②Hepatitis B virus (HBV) infection and HBV DNA positive (>1×10^3 copies/mL or >500 IU/mL), hepatitis C virus (HCV) infection and HCV RNA positive (>1×10^3 copies/mL or >100 IU/mL), human immunodeficiency virus (HIV) test positive; ③ poorly controlled diabetes, hypertension, thyroid disease, etc.; ④ severe and uncontrollable lung disease (severe infectious pneumonia, interstitial lung disease) Etc.) (≥CTCAE level 3); ⑤Severe infections that cannot be controlled (≥CTCAE level 3). With any situations that the researcher considers inappropriate to participate in this research.