Abstract: A new design of interactive control scheme is presented for the regulation of pH and DO in the mass culture of animal cells. It is simply composed of four-gas (air, oxygen, carbon dioxide and nitrogen) coupling compensating calculation (CCC) and multiple-sequence-control (MSC). By a series of logic judgements of signals from sensors and direct digital calculations (DDC), a simple proportional plus integral (PI) controller can manipulate the operations of electrocegnetic valves to meet the requirements of pH and DO levels in the growth and metabolism of animal cells.