Objective To investigate the effect of double fenestration branch stents on blood flow after different degrees of implantation in the thoracic aorta based on clinical statistical examples. Methods The thoracic aorta, thoracic aorta coated stent and branch vessel coated stent were established, and the branch stent was implanted into the diseased aorta in different degrees (5mm, 10mm, 15mm) by finite element method. The experiment was verified by in vitro tachymetry experimental platform. Results There was a certain rule for maintaining stable perfusion of blood flow field with different degree of branch stent implantation in thoracic aorta, Among them, the branch blood perfusion rate of group D10-5 was at a good level, and MAX TAWSS was at the lowest level of 44.94Pa, which was the group with the best simulation results.Conclusions Under the condition that the left subclavian artery (LSA) branch stent implantation in the thoracic aorta is short, the depth of left common carotid artery (LCCA) branch stent implantation in the aorta is appropriately increased to obtain a more stable blood flow field, which provides theoretical reference for the clinical practice of double fenestration technology.