Abstract: To investigate the deposition characteristics of pathogen-carrying aerosols within the respiratory tract, this study employs the numerical simulation method of computational fluid dynamics (CFD), coupling an evaporation/hygroscopic model with a discrete phase model. Focusing on hygroscopic bioaerosols with typical particle sizes, the study explores their hygroscopic behavior and deposition distribution patterns within a realistic human respiratory tract, and quantifies the influence of inhaled particle size, inhalation pattern, and indoor environmental parameters on the above process. The research indicates that the inhaled particle size and inhalation pattern of hygroscopic bioaerosols affect their hygroscopic growth rate and deposition distribution within the respiratory tract, with smaller particle sizes exhibiting a more pronounced change in the hygroscopic growth rate; for the same particle size, the hygroscopic growth rate of droplets inhaled via the nasal cavity is higher than that via the oral cavity in the upper respiratory tract. Compared to the environment of 26 ℃ and 60% humidity, the deposition amount of equilibrium size droplets in the upper respiratory tract is larger in the 18 ℃ and 40% humidity environment, and the effect is more significant for larger particle sizes. This study reveals the necessity of incorporating the hygroscopic growth mechanism of bioaerosols into the respiratory tract model, which is expected to provide a theoretical basis for precise prevention and control strategies against respiratory infectious diseases.