A device for monitoring body fluid discharge almost in real time is provided, the device includes a base, a motor, a catheter holder, and a liquid level sensor. The motor is fixed on the base and includes an output shaft. The catheter holder is connected to the output shaft and is rotatable relative to the base by the output shaft. The catheter holder includes a curved holding chamber with two openings containing a catheter. The liquid level sensor is disposed at one of the openings for detecting a liquid level of body fluid in the catheter and such level is recorded when a fully-filled catheter is automatically tipped and emptied into a collecting bag. A method for monitoring body fluid discharge using the device is also provided.