A server device has a case, a backplane board mounted inside the case, a plurality of data storage device replacement mechanisms inserted inside the case, a plurality of first data storage devices and a plurality of second data storage devices. The data storage device replacement mechanism includes a tray, a connector assembly and a circuit board. The connector assembly is disposed inside an accommodation space of the tray and includes a first connector and a second connector. The circuit board is installed inside a second arrangement area of the tray and electrically connected to the first connector, the second connector and the backplane board. The first data storage device is arranged inside a first arrangement area of the tray and electrically connected to the first connector. The second data storage device is arranged inside the second arrangement area of the tray and electrically connected to the second connector.