Diseased heart valves can be replaced with bileaflet mechanical heart valves (BMHVs), which may be affected by complications such as hemolysis, platelet activation and device failure. These complications are closely related to the characteristics of blood flow through mechanical valves and leaflet dynamics, and can become worse with tilted implantation of BMHVs. This study simulated the interactions of blood flow and leaflet motion for BMHVs implanted at different tilt angles. A fluid-structure interaction (FSI) method was employed to solve the problems of blood flow and leaflet motion interactively. A validation of the present numerical methods was performed against data produced in a previous work, indicating that the method presented in this study is reliable. Our results reveal detailed blood flow and leaflet motion in an aorta caused by the systole and diastole of the ventricle. As the tilt angle increased, the degree of asymmetry of blood flow and the time delay in the motions of the two different leaflets also increased, which may cause worsening of complications.