Abstract: Multi rate digital control technique has received special attention in chemical industry recently because of its good performance and strong adaptability. This paper briefly surveys the evolution history of multi rate digital control technique，and introduces the present theoretical and application research on multi rate control system. Furthermore，the existing difficulties in the research，such as data-losing and time-delay，are discussed，and corresponding approaches taken are also analyzed. Finally，the research trend of the technique is presented，with an emphasis on potential applications.