System informatization is a synthetic application which combines control science, computer science and network technology. Informatization technology is more and more applied in industry control system because of its simple structure, easy maintenance and high reliability. This article reviews the development history of informatization, and introduces its current research statuses. Based on the basic theories and composition of informatization systems, this paper deals with the problem of observer and controller design for a class of informatization systems where the network connection only exists between the sensor and controller. Finally, the future developments of informatization system are outlined.