The complex gas-solid two-phase flow in a full-sized solid rocket motor with embedded nozzle under different acceleration condition was simulated with Euler-Lagrange model. Influences of different particle diameters and acceleration conditions on particle trajectories were analyzed. Simulation results show that the difference between gas flow field and two-phase flow field is significant. The particle accumulation zone above inner wall of chamber and nozzle is mainly concentrated in two regions. The accretion of the particle diameter will cause the following property worse, and the particles can easily form a highly-concentrated aggregation flow. With the increasing of axial-acceleration, the impact point in line2 will move backward in rear head.