Nanocomposite tool materials are very important in engineering field for their advantage in mechanical properties and have a good foreground in the coming years. However, there are lots of puzzles in the materials design theory. So in this paper, a new nanocomposite tool materials design method is proposed based on the interface debonding theory. The wild phase content can be fixed by calculating the debonding interface rate and the strength requirement of the tool materials. Therefore, an experiment is carried out to fabricate WC based nanocomposite tool materials under the guider of the interface debonding theory. Results show that the experimental data is in accordance well with the calculation and the model is proved to be correct.