The invention discloses a gastrointestinal fluid pressure reducing device for the gastrointestinal surgery department. The gastrointestinal fluid pressure reducing device comprises a drainage pipe anda storage bucket, the storage bucket comprises a first bucket and a second bucket internally provided with liquid level sensors, a liquid inlet corresponding to a liquid drainage opening of the firstbucket is formed in the upper end of the second bucket, an electromagnetic valve is arranged on the liquid drainage opening, a groove is formed in the lower end of the first bucket, a protrusion structure matched with the groove is arranged at the upper end of the second bucket, an input pipe is arranged at the upper end of the first bucket and is inserted into a sucking pump and a controller inside the first bucket, an air purification chamber and an ozonator are arranged at one side of the first bucket in sequence, an inlet of the air purification chamber is connected with an output pipe ofthe sucking pump, an outlet of the air purification chamber is connected with the input end of the ozonator, the output end of the ozonator is connected with an air outlet pipe device, an isolation hood sleeves the drainage pipe, elastic strips are arranged at the two sides of the isolation hood, a sterilization chamber is arranged at one side of the second bucket, and an ultraviolet lamp is arranged inside the sterilization chamber. The gastrointestinal fluid pressure reducing device is high in drainage speed and good in pressure reducing effect, and gas is sterilized to be prevented from polluting the environment.