Numerical and experimental study on the gas-particle flow field has been carried out in the large Opposed Multi-Burner (OMB) Gasifier (I.D. 1.0 m) at high temperature and pressure. A 3D numerical model based on the Eulerian-Lagrangian model is used to simulate the gas-particle flow behaviors. The gas phase is treated as continuous phase with an Eulerian method while the Lagrangian method is applied to trace of the particles, and the interaction between gas and particles is considered. The behavior of slag/ash particle collision and its effects on particle dispersion are presented. The simulations are validated by available experimental data. The results showed that material residence time increased with the straight section height above the burner, and the deposition flux increased with the inlet velocity. The axis profiles of particle concentrations at high temperature and pressure have the similar characteristic shapes to those at ambient pressure and temperature. And the highest turbulence intensity and collision flame are converged around the centre of impingement zone. Though the inter-particle collision led to the phenomenon of particle agglomeration, the holistic distribution of particle concentration was reasonable. Finally, the effect of operating pressure and particles Stokes number were studied. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.