Aim: To study comparatively the effects of different implantation angles of bi-leaflet mechanical valve on the swirling flow in the ascending aorta. Method: Based on the aortic CT images of a healthy volunteer, using a computational simulation, the effects of 4 different valve implantation orientations (0 ° , 45 ° , 90 ° and 135 o) on the aortic rotational flow were studied. Results: The results showed that the implantation of BMHV can seriously interfere with the aortic rotational flow, affecting the structure and helicity distribution of the rotational flow in the ascending aorta, and resulting in disturbed blood flows distal to the valve. For the case studied in this paper, the 135-degree implantation angle caused the most disruption to the swirling flow, leading to the largest areas of reversed rotational flows, while the 0-degree and 45-degree implantation angles caused relatively less damage to the swirling flow. The areas with low wall shear stress (WSS less than 0.5 Pa) was the smallest when the implantation angle of BMHV was 0 o. Conclusions: When the implantation angle was between 0 o and 45o, the disruption of BMHV to the swirling flow in the ascending aorta was relatively small. Therefore, for different patients, the choice of the implantation angle should be individualized according to the spatial geometry of their aorta, including the aortic sinuses.