The main purpose of the UNL (Universal Networking Language) is enabling people in the world can access information on the Internet in using their own language without any barriers of language. Currently, there are many research projects to apply UNL for different languages, but it is still very limited for the Vietnamese. In this paper, we propose solution to build dictionary Vietnamese - UNL. First, we extract automatically the vocabulary of UNL expression, then compare its headword with the headwords in the dictionary English - Vietnamese and if matches, we will replace the content of item. Then, the language experts will participate to postedit the dictionary Vietnamese - UNL. As a result, we have to extract 205,102 entries and approximately 1,153 items from being edited. This is an important step in the process of integrating Vietnamese into the system UNL
