According to the problems of the numerical calculation of the gas-solid two-phase flow field in the design adiabatic structure of the solid rocket motor (SRM), the 3-D two-phase inner flow field at end of burning in a SRM under overload conditions with the method of Euler-Lagrange, the SST (shear-stress-transport) kω turbulence model and the particle trajectory model (PTM) were used, and PSIC method were employed to solve equation sets. The internal pressure and temperature fields, gas and particle velocity fields, solid-phase particle deposition concentration and particle trajectory of the SRM under two cases were calculated. The concentration of particles in different parts of SRM was analyzed emphatically. The results demonstrate that the particles move in the opposite direction of the transverse overload, and the hysteresis effect is evident, so is likely to hit the nozzle convergence. The change of pressure, temperature and the flow velocity fields of SRM in two cases are very close. The highest particle deposition concentration is generated in the inner wall of the insulating layer of the SRM rear head, resulting in the particle congregation and the low velocity vortex flow phenomenon. With the constantly burning propellant, the average particle deposition concentration near the wall of the adiabatic layer shows an upward trend.