Ultrasonic and acid-base cleaning of the inner wall of the tube can make it clean enough to meet the requirements of trace element detection. The dense rubber plug membrane treatment can effectively prevent the rubber plug precipitation. The inner surface of the tube can make the platelet activity in a moderate state, the blood coagulation process is smooth, the blood clot shrinks normally, and the competitive adsorption process of protein is fully inhibited, So as to provide a sufficient amount of non polluting serum samples for clinical test, so that the serum components remain unchanged in a long test cycle, with high repeatability.