The leaflet vibration phenomenon in bileaflet mechanical heart valves (BMHVs) can cause complications such as hemolysis, leaflet damage, and valve fracture. One of the main reasons for leaflet vibration is the unsteady blood flow pressure pulsation induced by turbulent flow instabilities. In this study, we performed numerical simulations of unsteady flow through a BMHV and observed pressure pulsation characteristics under different flow rates and leaflet fully opening angle conditions. The pressure pulsation coefficient and the low-Reynolds k-ω model in CFD (Computational Fluid Dynamics) software were employed to solve these problems. Results showed that the level of pressure pulsation was highly influenced by velocity distribution, and that the higher coefficient of pressure pulsation was associated with the lower flow velocity along the main flow direction. The influence of pressure pulsation near the trailing edges was much larger than the data obtained near the leading edges of the leaflets. In addition, considering the level of pressure pulsation and the flow uniformity, the recommended setting of leaflet fully opening angle was about 80°.