The invention discloses a postoperative drainage liquid detecting system used in the thyroid and breast surgery department. The postoperative drainage liquid detecting system comprises a placement box, wherein waste liquid placement seats are symmetrically arranged at two ends of the inside of the placement box, waste liquid tanks are arranged in the waste liquid placement seats, seal caps are arranged at the upper ends of the waste liquid tanks, the upper ends of the seal caps are connected with handles through negative pressure pipes, negative pressure regulating blocks are arranged at the front ends of the handles, intelligent regulating modules are arranged in the negative pressure regulating blocks, monitoring modules are arranged at the front ends of the negative pressure regulatingblocks, body fluid meters and body fluid property detection sensors are arranged in the monitoring modules, pipe connectors are arranged at the front ends of the monitoring modules, air pressure sensors are arranged in the seal caps, display screens are arranged at the upper ends of the seal caps, the upper ends of the seal caps are connected with negative pressure pump devices through the negative pressure pipes and control valves, and a control box is arranged in the placement box. The postoperative drainage liquid detecting system is stable in structure, simple in operation, capable of achieving remote control and data sharing and achieving a drainage detection function and intelligent regulation and convenient to use and operate and meets the existing use requirements.