A stochastic model of heavy particle dispersion is proposed.It is based on the coupling of the stochastic equation of turbulent fluid motion with the heavy particle crossing trajectory equation in which Saffman force,particle-wall collision and particle-particle collision are included.The model is also tested in a turbulent boundary layer with heavy particles.The numerical results are in good agreement with previous experimental data.The effect of Saffman force and particle collision on the heavy particle dispersion is investigated numerically as well.