Abstract: CHO cells expressing anti-CD3 and Claudin 18.2 bispecific antibodies were used to optimize the perfusion culture process and reduce bispecific antibody aggregation. A definitive screening design （DSD） was employed to evaluate the effects of four excipients—trehalose, sucrose, glucose, and mannitol—as culture medium additives on the formation of bispecific antibody aggregates during the perfusion cell culture process. Based on the experimental results, prediction models were established between these four excipients and two critical quality attributes: aggregate level and antibody-specific productivity （q_P）. The optimal perfusion conditions for reducing bispecific antibody aggregates were determined to be 32 mmol·L⁻¹ trehalose, 50 mmol·L⁻¹ sucrose, 8 g·L⁻¹ glucose, and 25 mmol·L⁻¹ mannitol. Under these conditions, the aggregate level decreased by 39.3%, and the antibody-specific productivity increased by 22.8%. These optimal conditions were successfully validated across different bispecific antibody molecules and cell lines, demonstrating excellent process applicability. In conclusion, the use of excipients as culture medium additives can effectively reduce aggregate levels and improve antibody-specific productivity during the perfusion culture of bispecific antibodies, providing a valuable technical reference for addressing the aggregation issues in bispecific antibody production.