Objective Discuss the application methods and effects of closed femoro?femoral partial bypass （C-FPB） in thoracoabdominal aortic replacement（TAAAR） surgery. Methods A retrospective analysis of the clinical data of 70 cases of TAAAR assisted by C-FPB from April 2021 to May 2023， some of which combined with abdominal organ perfusion. The main evaluation indicators were in-hospital mortality， postoperative stroke， postoperative spinal cord injury， and the incidence of hemodialysis. Based on an open-type conventional Cardiopulmonary bypass（CPB）circuit， the venous tubing was split with a 10 × 10 × 10 mm "Y" connector directly connected to the inlet of the centrifugal pump， and the tubing after the roller pump was connected to the outlet of the centrifugal pump， while the front of the membrane oxygenator with another 10 × 10 × 10 mm "Y" connector to establish a closed femoro-femoral bypass. During bypass， the lower body is perfused by the centrifugal pump， while the upper body is perfused by the roller pump. Results No system failures happen in all cases. The average bypass time was （101.0 ± 22.2） minutes， the average time for intercostal artery reconstruction was （18.6 ± 5.4） minutes， with an average of （4.7 ± 1.8） pairs. The average length of stay in the ICU was （5.1 ± 1.5） days， and the average length of hospital stay was （34.4 ± 12.5） days. 2 cases （2.9%） experienced postoperative stroke， 1 case （1.4%） resulted in in-hospital mortality， 2 cases （2.9%） experienced postoperative paraplegia， 7 cases （10.0%） underwent postoperative hemodialysis， and 3 cases （4.3%） experienced prolonged mechanical ventilation. Conclusion The Closed-type femoro-femoral partial bypass takes the whole surgical process into account， reduces the management difficulty for perfusionist， and provides a unique advantage for distal perfusion during thoracoabdominal aortic replacement surgery.