Abstract: In order to obtain the dynamics of the deposition distribution of Fe particles in the transcritical region in the heating surface of the boiler of the supercritical unit, a two-dimensional model of the horizontal circular tube was established. The distribution of particle deposition was studied by changing the inlet temperature, inlet flow rate, wall heating power, particle force and particle diameter. Results show that particle size is the main factor affecting the kinetic process of particle deposition. For particles with a particle size greater than 1.0 μm, the forces that inhibit particle deposition are Saffman lift force, thermophoresis force and Brownian force. While the particle size is less than 1.0 μm, the forces that inhibit the particle deposition are thermophoresis force, Saffman lift force and Brownian force in descending order. When the particle size is 2.0 μm, it has the best deposition effect in the transcritical region, and with the increase of inlet flow velocity, the peak concentration of particle deposition gradually decreases, and the deposition position moves to the outlet of the pipe. With the increase of wall heating power, the total amount of 8.0 μm particles deposited won't change much.