Inclusion Criteria:  Patients with histologically or cytologically confirmed unresectable locally advanced or metastatic solid tumors which is relapsed or refractory to standard treatment, or lack of standard treatment, or standard treatment is not applicable currently; Have at least one measurable tumor lesion per RECIST v1.1 (patients with only non-target lesions are allowed to be enrolled in dose escalation stage); ECOG performance status of 0-1; Life expectancy ≥ 12 weeks; Adequate bone marrow and organ function . Subjects must voluntarily agree to participate in the trial and sign a written informed consent form.  Exclusion Criteria:  Patients with symptomatic central nervous system metastases or meningeal metastases; Ongoing or previous anti-tumor therapies within 4 weeks prior to the first dose of study drug; Prior treatment with antibody-drug conjugate (ADC) consisting of topoisomerase I inhibitors; History of serious cardiovascular and cerebrovascular diseases; Severe infection within 4 weeks prior to the first dose; Adverse reactions of previous anti-tumor treatment have not recovered to Grade ≤ 1 per NCI-CTCAE v5.0.