A door mechanism assembly, applying to an electronic device, wherein the electronic device includes a housing and an electronic connector, and the housing includes an opening and a guide groove, including: a movable unit, disposed in the housing, wherein the movable unit includes a body, a first magnetic member, and a push rod, the electronic connector is disposed in the body, a connection interface of the electronic connector corresponds to the opening, the first magnetic member is disposed in the body, one end of the push rod is connected to the body, the other end of the push rod stretches into the guide groove and is able to move back and forth along the guide groove, and the body is driven by the push rod to move from a first position toward the opening to a second position; and a door unit, including a cover panel and a second magnetic member, wherein the cover panel is able to move back and forth between a closed position and an opened position relative to the housing, the cover panel covers the opening at the closed position, the opening is exposed when the cover panel is at the opened position, the second magnetic member is disposed on the cover panel, and the first magnetic member is magnetically repulsive to the second magnetic member; wherein the door mechanism assembly is characterized in that: the movable unit further includes a rail, the rail is disposed in the housing and extends toward the opening, and the body is disposed on the rail and is able to move back and forth between the first position and the second position; wherein when the body of the movable unit moves to the second position, the relative positions of the first magnetic member and the second magnetic member overlap and thus a magnetic force is generated, the magnetic force pushes the cover panel to the opened position, and the connection interface of the electronic connector is exposed in the opening. a movable unit, disposed in the housing, wherein the movable unit includes a body, a first magnetic member, and a push rod, the electronic connector is disposed in the body, a connection interface of the electronic connector corresponds to the opening, the first magnetic member is disposed in the body, one end of the push rod is connected to the body, the other end of the push rod stretches into the guide groove and is able to move back and forth along the guide groove, and the body is driven by the push rod to move from a first position toward the opening to a second position; and a door unit, including a cover panel and a second magnetic member, wherein the cover panel is able to move back and forth between a closed position and an opened position relative to the housing, the cover panel covers the opening at the closed position, the opening is exposed when the cover panel is at the opened position, the second magnetic member is disposed on the cover panel, and the first magnetic member is magnetically repulsive to the second magnetic member; wherein the door mechanism assembly is characterized in that: the movable unit further includes a rail, the rail is disposed in the housing and extends toward the opening, and the body is disposed on the rail and is able to move back and forth between the first position and the second position; wherein when the body of the movable unit moves to the second position, the relative positions of the first magnetic member and the second magnetic member overlap and thus a magnetic force is generated, the magnetic force pushes the cover panel to the opened position, and the connection interface of the electronic connector is exposed in the opening. the movable unit further includes a rail, the rail is disposed in the housing and extends toward the opening, and the body is disposed on the rail and is able to move back and forth between the first position and the second position; wherein when the body of the movable unit moves to the second position, the relative positions of the first magnetic member and the second magnetic member overlap and thus a magnetic force is generated, the magnetic force pushes the cover panel to the opened position, and the connection interface of the electronic connector is exposed in the opening.