The hydrodynamics and solids mixing behavior in a riser with blunt internals are studied. A uniformradial distribution for solids fraction and particle velocity achieves near the internals. The turbulent velocityof particles near the wall increases with the addition of the internals, with the lateral solids mixing enhancedsignificantly. Probability density distribution of particle velocity is bimodal in the riser with internals, which issimilar to that in the conventional riser, indicating that no significant difference in the micro flow structure existsbetween the riser with internals and the conventional riser. At the same time, the axial solids mixing behaviorchanges insignificantly with the addition of internals. These results indicate that the micro flow structure in theriser is very stable, which changes insignificantly with the change of the bed structure.