The invention discloses a multifunctional postoperative negative pressure drainage device, which comprises a negative pressure drainage pipe, a detection device, a negative pressure drainage device and a drainage liquid collector. A drainage pipe fixing and clamping sticker is arranged at one end of the negative pressure drainage pipe. The other end of the negative pressure drainage pipe is connected with the drainage liquid collector. An anti-bending support, the detection device and the negative pressure drainage device are arranged on the negative pressure drainage pipe. An alarm is fixedlyarranged at the top of the drainage liquid collector. The side wall of the drainage liquid collector is provided with a main control console, an auxiliary pressure pump and an observation window. Theauxiliary pressure pump is connected to an inner cavity of the drainage liquid collector through a pipeline. A transparent graduated scale is arranged on the observation window. The bottom of the drainage liquid collector is connected with a liquid outlet pipe through a pipe hoop, a liquid level meter is installed on the inner wall of the cavity of the drainage liquid collector. The negative pressure drainage device has the advantages of simple operation, good negative pressure precision control effect, convenient adjustment, good liquid discharge effect and the like.