Most of Microcomputers based on Intel 80386/486 CPU can run the XENIX Operating System. But the XENIX kernel have to be modified, expanded, and exploited tomeet the need of users in China. Even since 1979, the authors study and develop UNIX and UNIX-like systems, and have more experiences. The authors have exstracted the XENIX kernel source code from the object code, by the computer-aided tools. In this paper, the exstraction method, the tools and the details for exstraction procedure are described.