To ensure the health and safety of astronauts during future manned lunar missions, it is critical to understand the transport and deposition of lunar dust (LD) particles in the terminal alveoli. This study employs computational fluid dynamics (CFD) to investigate the deposition characteristics of LD particles, considering factors such as particle size, activity intensity, and body posture. The key findings are: (1) The deposition characteristics of LD particles differ significantly across various activity intensities, with higher activity levels resulting in earlier onset and shorter duration of deposition. (2) The distributions and rates of deposited particles on the alveolar wall vary with different body postures. Specifically, transitioning from a head-up to a head-down posture leads to a reduction of 4.51 times in deposition time. (3) A predictive equation has been developed that effectively estimates LD particle deposition in the terminal alveoli by accounting for particle size, activity level, and body posture. In conclusion, LD particles display diverse deposition characteristics in the terminal alveoli, which can be accurately predicted using an appropriate fitting equation. The findings of this study may significantly enhance astronaut safety and well-being during future manned space exploration missions.