Reserved line for digital information transmission and protection device for preventing plug from falling off

The invention relates to the technical field of digital information transmission, and discloses a reserved line for digital information transmission and a protection device for preventing a plug fromfalling off, and the device comprises a housing; through the cooperative use of a negative pressure chamber, a piston, a push rod and a socket pedestal, negative pressure can be generated after the socket pedestal is connected with the plug, thereby enabling the connection to be more stable, preventing the fall-off of the plug from causing the power failure, and enabling the power connection to bestable; through the cooperative use of the roll shafts and the limiting blocks, so when the connecting wires are connected to form an access, if the connecting wires are kicked by feet accidentally,enough length is reserved, the connecting wires are automatically stretched, and the connecting wires are prevented from being broken due to hard stretching; meanwhile, the connecting wires are prevented from forming a pulling