The analog controller of a certain turbofan engine generally exisits the defects, in practice, such as that it doesn't match the engine in life-span, is poor in monitoring faults, gives the wrong alarm and so on. In order to solve these problems, taking the Digital Electronic Controller (DEC) as a studying object, we designed the hardware and software structure of the DEC. And also we designed two hardware systems to enhance the reliability of the DEC. The two hardware systems worked at the same time and the backup system received the main system's information every moment, thus keeping the switch process stable. Finally the experiment result of the DEC is given. The result indicates that the research and argumentation for the design of the DEC is reliable and reasonable.