Abstract: Many existing types of FS developed to address different application cases demand the OS to support concurrent accessing to different type of FS instance.This paper discribes the technique for supporting serveral of types file system under UNIX operating system-the vnode/vfs interface,and analyzes its implementation in AIX 4.1.1.There are some problems and difficulties for vender to implement his own file system with new functions.In this paper,an easy method is presented to reslove these problems by using existing file system code to simplify the implemetnation of new FS.