Abstract: Described in the article are the advantages and disadvantages of the steel tube storage-transfer systems as common-used in the oil casing production line,i.e.,the sloping skid bed and the declined chain type conveyer. It is proposed to mount a flexible stopper device onto the said skid bed for separating,storing and transferring tubes. Based on relevant analysis,the operation principle and loading conditions of the stopper device are identified,i.e., once the tube contacts the stopper,its right end is pressed down,while its left end goes up to stop the tubes following;and on the other hand,when the tube is getting off the stopper,its right end rises,while its left end falls beneath the skid bed,and thus the next tube is allowed to enter. This flexible stopper possesses such advantages as simplified structure,running without any power,light,low initial investment,and function of protecting tubing/casing threads,etc. Actual operation has proved the high effectiveness of the stopper device.