Abstract: Aiming at the melting and slagging phenomenon of ash particles in the high temperature superheater tube bundle of biomass boiler, a viscous deposition model combining inertial impaction mechanism and melting adhesion mechanism was selected to simulate the deposition characteristics of fly ash in different structural tube bundles in the high temperature superheater region of biomass boiler. The results show that the first row of the in-line tube bundle is the main composition of deposition, and the first two rows of the staggered tube bundle are the main composition of deposition. Due to the shielding effect of the front row, there is a small amount of deposition in the back row of the tube bundle; The influence of flue gas velocity on deposition distribution is weak; The total deposition efficiency of the in-line tube bundle is 14.7 %, and that of the staggered tube bundle is 50 %, indicating that the staggered tube bundle is prone to viscous deposition during actual operation. The in-line structure can reduce the risk of blockage of the high temperature superheater tube bundle.