In order to meet the requirements of portable office, the paper proposes a method to construct a mini personal system, which uses Linux kernel and components, on the portable and removable USB storage device. The key components of the system, which includes kernel compiling, LFS, AUFS, Grub and so on, are researched and analyzed deeply in the paper. At the same time, the details of the entire constructing process about transporting and system booting are illustrated as well. The new system proposed by the paper has four advantages as follow: smart and portable, a shorter booting time, a lower memory cost and more reliability. The features of the system makes it have bright application fields.