This is an open-label, multi-center phase II study of IBI3003 in combination with anti-CD38 monoclonal antibody in adult subjects with multiple myeloma. This study includes a safety run-in period and 2 cohorts (Cohorts 1 and 2).In the safety run-in period, subjects with measurable relapsed or refractory multiple myeloma who had previously received at least 1 line of systemic anti-myeloma therapy and had a history of dual drug exposure (at least one proteasome inhibitor and one immunomodulatory agent) were enrolled, mainly to evaluate the safety and tolerability of IBI3003 in combination with anti-CD38 monoclonal antibody and to determine the recommended phase 2 dose of IBI3003 in combination with anti-CD38 monoclonal antibody.Cohort 1 mainly enrolls newly diagnosed MM(Multiple myeloma)patients who are ineligible for or refusing ASCT(Autologous Stem Cell Transplantation), and Cohort 2 enrolls newly diagnosed MM patients who are eligible for and willing to undergo ASCT. The 24-week MRD negative rate of IBI3003 in combination with anti-CD38 monoclonal antibody in the participant population is mainly evaluated.