Nowadays, nanocomposite tool materials are very important in engineering field for their excellent mechanical properties and stability under high temperature and have a good foreground in the coming years. However, there are lots of puzzles to be discussed in the materials design theory and the fabrication processing due to the difference between the traditional materials and the nanocomposite. In this paper, a new tool materials design method is proposed based on the interface strengthening theory. The sintering temperature and the soaking time are optimized based on the interface strengthening theory and the relative density of the tool materials is also discussed. The wild phase content can be fixed by calculating the debonding interface rate and the strength requirement of the tool materials. Meanwhile, a series of experiments are carried out to fabricate and optimized the nanocomposite tool materials under the guider of the interface strengthening theory. Results show that experimental data is in accordance well with the calculation and the interface strengthening theory.