<p>The deposition of aerosol particles within microchannels is a significant phenomenon with profound implications for various fields, such as air pollution control, respiratory disease prevention and advanced manufacturing. However, the mechanisms underlying the combined effects of thermophoresis, diffusion, and deposition of particles in rectangular channels under laminar flow conditions with slip flow velocity boundary conditions remain unclear. We theoretically analyze the variation of deposition velocity with aerodynamic particle size under different deposition mechanisms (such as diffusion, sedimentation and thermophoresis), and obtain the general analytical solutions for deposition velocity, concentration, mean concentration and deposition efficiency for particles. The results indicate that the combined mechanisms should be considered for particles from 0.06 to 0.3&#xa0;µm, and the particle concentration under the slip velocity boundary condition is always larger than that under the non-slip velocity boundary condition. The particle concentration profile peak deviates from the center axis of the channel by increasing deposition parameter (denotes the relative importance of sedimentation, thermophoresis and diffusion on the particle deposition onto the channel walls). Moreover, the particle mean concentration decays with the increase of the deposition parameter, and the ones under the slip velocity condition are larger than those under the non-slip velocity condition. Our findings of this study provide insights for aerosol deposition in a narrow rectangular channel due to multiple mechanisms under the slip velocity boundary conditions.</p>