Abstract: The hydrodynamics of a three-dimensional double slot-rectangular spouted bed with two uniform chambers and two parallel slots are numerically studied by means of the parallel CFD–DEM coupling approach. In the coupling framework, the gas flow is described using the Navier–Stokes equations while the particles are tracked with the discrete element method. The start-up procedure and the typical flow structure of the system are explored in a microscopic view. Then, the distribution properties of the bed hydrodynamics are investigated. Moreover, the influence of turbulence model on gas–solid motion is discussed. Finally, the specialty of double slot-rectangular spouted bed is explored as compared with one chamber system. The results show that four distinct stages can be identified in the startup procedure. In the steady operation, the particles of each individual chamber of the bed interact with each other in the fountain region and the intensity initially increases and then decreases along the bed height. Excellently symmetrical properties can be obtained for the gas velocity, the voidage and the solid flux with a peak appearing in the central part of each individual chamber. Moreover, unequal size of the slot in the width and depth influences the distribution properties of these important parameters. The gas turbulent effect on the gas–solid motion is weak in the annulus region but explicit in the spout and fountain region. Five typical flow patterns can be observed in the double slot-rectangular spouted bed.