A plug-in device, comprising: a circuit board having a support face; a first connecting piece arranged on the support face, and provided with a first contact terminal, wherein the first contact terminal is electrically coupled to the circuit board; a card tray comprising a first mounting face facing the first connecting piece and a second mounting face; wherein the first mounting face and the second mounting face are respectively arranged on opposite sides in a thickness direction of the card tray, the first mounting face is configured to place a first chip card in electrical contact with the first contact terminal, and the second mounting face is configured to place a second chip card electrically coupled to the circuit board; a side face of the card tray is provided with a first limiting portion, and the first limiting portion is a groove; a second connecting piece located above the second mounting face; and a housing fixed on the circuit board, wherein the card tray is arranged in the housing, and the second connecting piece is fixedly coupled to the housing; the housing is provided with a second limiting portion, and the first limiting portion matches with the second limiting portion to limit relative movement of the card tray and the housing; the housing comprises an elastic piece arranged along a direction in which the card tray is plugged in or pulled out the housing, and the second limiting portion is a protrusion formed on the elastic piece; and the protrusion is engaged in the groove; the housing comprises a top wall parallel to the second connecting piece and a side wall connected to and perpendicular to the top wall; characterized in that the side wall defines an opening, the elastic piece is located in the opening, and two opposite ends of the elastic piece are connected to the side wall. a circuit board having a support face; a first connecting piece arranged on the support face, and provided with a first contact terminal, wherein the first contact terminal is electrically coupled to the circuit board; a card tray comprising a first mounting face facing the first connecting piece and a second mounting face; wherein the first mounting face and the second mounting face are respectively arranged on opposite sides in a thickness direction of the card tray, the first mounting face is configured to place a first chip card in electrical contact with the first contact terminal, and the second mounting face is configured to place a second chip card electrically coupled to the circuit board; a side face of the card tray is provided with a first limiting portion, and the first limiting portion is a groove; a second connecting piece located above the second mounting face; and a housing fixed on the circuit board, wherein the card tray is arranged in the housing, and the second connecting piece is fixedly coupled to the housing; the housing is provided with a second limiting portion, and the first limiting portion matches with the second limiting portion to limit relative movement of the card tray and the housing; the housing comprises an elastic piece arranged along a direction in which the card tray is plugged in or pulled out the housing, and the second limiting portion is a protrusion formed on the elastic piece; and the protrusion is engaged in the groove; the housing comprises a top wall parallel to the second connecting piece and a side wall connected to and perpendicular to the top wall; characterized in that the side wall defines an opening, the elastic piece is located in the opening, and two opposite ends of the elastic piece are connected to the side wall.