Abstract: A manual/automatic operation interchangeable connecting seat of ball valve is disclosed. The connecting seat is formed with a central shaft hole through which a controlling lever of a ball valve body extends. Two ear sections are formed on two sides of the connecting seat. Each of the ear section has a central through hole corresponding to a connecting hole of a top flange of the ball valve body. A thread rod goes through the through hole of the ear section and the connecting hole of the top flange to secure the concectins seat on the ball valve body and seal the same. Each ear section has two wing portions on two sides thereof and each wing portion has an opening for engaging a driver with the connecting seat in automatic operation mode of the ball valve, whereby the controlling lever can be associated with a grip in manual operation mode of the ball valve or alternatively associated with a driver to change the manual operation mode into automatic operation mode of the ball valve.