Abstract: The microcomputer principles is a practical course, it is urgent to solve the problem of its course practice to improve the course teaching effect and enhance the student's experiment ability and innovation ability. The shortcoming of teaching of this course was analyzed, the simulation software of Proteus and Emu8086 was introduced to design simulation experiment to solve the problem of practice and teaching. Traffic light experiment with 8086 and 8255A was employed to carry into simulation experiment of 8086. It is indicated that the traffic light simulation experiment reach the simulation of 8086, which solve the problem of practice of microcomputer principles and provide a new method to improve the teaching skill of this course.