Determination of inhaled particles deposition in human lung is very important forestimation of the health risk of particulate air pollution and optimization of drug delivery by inhalation.A one-dimensional dynamic transport model or so-called "trumpet" model was developed to evaluate the fate of particles due to mechanisms of inertial impaction, gravitational sedimentation and Brownian diffusion.Particles having densities of 100, 1000 and 4000 kg/m3 in the size range of 0.01-10 μm were investigated.The deposition mechanismsin relation to particle sizes and densities were also assessed.The results showed that for particles smaller than 0.1 μm, deposition is only due to diffusion and independent of mass density; for particles larger than 0.1 μm, the sedimentation and impaction sequentially exert a significant effect, and deposition significantly depends on mass density.The present work indicates that particle size and density are two essential factors to affect deposition pattern of particles in the lung andonly one or two mechanisms usually play a dominant role.