The aim of this study was to solve the existing problems of sealing device for mouth-closed iron drums such as slow searching speed, low sealing efficiency and poor reliability. A sealing device was designed, which fixed sprue using visual positioning technique, and the two processes of cap screwing and cap pressing were simultaneously finished at the same work station. The mouth was located quickly and precisely. Only one localization was required for the completion of the two procedures of cap screwing and cap pressing. The practical application showed that the device was reliable and had high sealing efficiency.