This work was aimed to design an eccentric bunghole cap screwing-pressing machine, in order to solve the problems of slow speed, low efficiency, and poor reliability in bunghole positioning and cap screwing-pressing. The bunghole center was automatically positioned using the robot vision positioning system. After coordinate transformation, the positioning information was transferred to the robot through TCP/IP communications, and the operations of picking up the cap, screwing the inner cap and pressing the outer cap using the rapidity and accuracy of the robot. The test system was built, numerical fitting was conducted for the coordinate transformation, and operations of screwing and pressing the cap were performed. As a result, the bunghole was positioned quickly and precisely with an positioning error of below 0.8 mm. Simultaneously, the two processes of screwing cap and pressing cap were finished at one localization. The practical application showed that the equipment was reliable, with rapid positioning ability and high sealing efficiency.