Liquid drainage bag capable of adjusting negative pressure value

The utility model discloses a drainage bag capable of adjusting a negative pressure value, which comprises a drainage bottle and a suction bottle, the suction bottle is provided with a coupling head, the coupling head is matched with a coupling pipe to be communicated with the drainage bottle, the suction bottle is provided with a negative pressure meter, the negative pressure in the suction bottle can be directly monitored, and medical staff can conveniently adjust the negative pressure value in real time. The negative pressure drainage device further has the following characteristics that the liquid drainage bottle connecting pipe connector is arranged at the top, so that the situation that discharged liquid is sucked into the suction bottle can be effectively reduced; the bottle cap is of a detachable structure, so that the suction bottle is convenient to clean and disinfect; a nylon sticker is arranged on the side part of the suction bottle and can be adhered and separated from the drainage bottle; the li