The utility model relates to a transfusion system that automatically closes and alarms then the dropping is over which mainly solve the problem of prior transfusion system that the transfusion needs to be attended to prevent accident incurred by the air entering the body because the needle is not pulled out in time after the dropping is over. The utility model comprises a dripping funnel equipped with a liquid inlet, an air venting outlet and a transfusion outlet and is characterized in that the dripping funnel is provided with a floater; the lower part of the floater is connected with a canister water injection valve; the upper end of the water injection valve is provided with a water inlet and the lower end is provided with an elastic film; and outside the dripping funnel and at the height of the floater in the transfusion status is provided with a photoelectric alarm device. The system has the advantages that alarm can be sent in time and the system can close automatically as the injection drips out. The use is safe and reliable, thereby reliving the labor intensity of the attending and the medical personnel and meeting the medical standard. Meanwhile, the cost is low.