A plug-in device may include a circuit board, a first connecting piece stacked on the circuit board and a card tray stacked on the first connecting piece. The card tray may include a first mounting face facing the first connecting piece and a second mounting face away from the first connecting piece. The first mounting face may be configured to place a first chip card electrically connected to the circuit board through the first connecting piece. The second mounting face may be configured to place a second chip card electrically connected to the circuit board. A projection of the first mounting face along a direction perpendicular to the first mounting face may overlap that of the second mounting face. A terminal may include the above mentioned plug-in device.