In this present paper, thermophoretic depositions of fine particles are used in a heated turbulent boundary layer over very small plate via two-fluid model, or Eulerian-Eulerian approach. The Prandtl’s mixing length model of turbulence is used for the closure problem. The governing equations of gas phase are coupled with the governing equations of particle phase in two-way model, while uses the particle diffusion term as another coupling term. The equations are solved numerically by using finite difference method. One can obtain the convergence by numerical calculations much easier than with no diffusion term. A vast amount of information can be extracted for this kind of modeling. The effect of important parameters such as diffusion factor, gravity and thermophoretic force are considered. The cooler temperature of plate results higher particles deposition or concentration on the flat plate. Also, the larger particle size diameters delay the maximum particles deposition further distance away from the plate front edge. The results give the correct physical prediction overall.