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 . <EOS>