Aluminum dust explosion has become an important type of dust explosion accident. In the present work, an interconnected system is established to study the influence of accumulated dust layers in connecting pipes on explosion propagation characteristics. A high-precision computational fluid dynamics (CFD) method is applied to study the overpressure and flame development of aluminum powder explosion under the central ignition condition of two cylindrical vessels with a volume ratio of 1:5. The results show that pressure build-up in the secondary container is mainly due to the oscillating pressure wave. Moreover, compared with the ignition container, the thickness of the dust layer has a more obvious enhancement effect on the peak overpressure for the secondary container. When the ignition occurs in a large container, the dust layer is lifted in the connecting pipe under the action of the precursor pressure wave. After the jet flame enters the connecting pipe, the lifted aluminum dust participates in the explosion reaction, which significantly increases the explosion intensity. With the participation of the accumulated dust layer, the maximum overpressure of the explosion of flake aluminum dust in the interconnected system is higher than 30 bar, and the jet flame velocity is increased by 3 times. The present work can provide reference for the safety design of process equipment involving dust.