During clinical surgery, any surgery will be accompanied by bleeding, if the gauze is used to estimate, clinically estimate the amount of blood loss of a piece of gauze. The gauze used in surgery is divided into large gauze and small gauze, large gauze stained with blood, blood loss is generally 20mL, if the small gauze stained with blood, blood loss is estimated to be about 5mL, which is only a rough clinical estimate. If the precise estimation of the blood loss of gauze, it is necessary to weigh the sterile gauze before the patient’s surgery, and then weigh the gauze containing blood again after the surgery, and subtract it from the weight value of the sterile gauze before the surgery, to get the difference between the two, and then add the amount of blood loss in the suction device, then the amount of blood loss in the patient’s surgical procedure can be accurately calculated. It is easy for the doctor to understand the whole process of the patient, and it will be helpful for the later treatment.