In the teaching process of the Microcomputer Principle and Application, the easy-to-understand method is adopted and it utilizes the decoder to simplify and indicate the process of addressing the memory unit by CPU because of the complex structure of the hardware and difficulty met at the beginning of the learning of it. In this paper, the author analyzes and summarizes the process of coordinated control of CPU and internal storage in completing the instruction in the process of microcomputer bus operation, which helps students understand the working principle and execution process of microcomputer software and hardware. And good results have been achieved in the practical teaching of the course.