An electronic device is provided. The electronic device includes a housing, a first riser module, a hard-disk backplane module, and a plurality of hard-disks. The first riser module is disposed in the housing. The first riser module includes a first tray structure and a first riser board. The first riser board is disposed on the first tray structure. The first tray structure is adapted to move the first riser board in a first direction. The hard-disk backplane module is disposed in the housing. The tray structure is adapted to move the first riser board in the first direction to connect the hard-disk backplane module. The hard-disks are connected to the hard-disk backplane module. The modules of the electronic device of the embodiment of the invention can be coupled together more easily.