We design a new microcomputer interface simulation system using Proteus and TPC-USB based on the existing experimental system of microcomputer principles, and expound the experiment synthesis design method of this system. This paper describes the main process of simulation and debugging of the system based on the simulation of voltage alarm system. In the design process of hardware experimentation, we combine the computer simulation system with the Proteus schematic edit, and use assembly language, C language or mixed programming way source code to do writing, debugging and running in TPC-USB platform. Practice shows that the experiment can deepen the understanding of knowledge points of microcomputer principle, further mobilize the enthusiasm of the students and improve capabilities of microcomputer principle integrated design.