Treebank is an important resource for both research and application of natural language processing. For Vietnamese, we still lack such kind of corpora. This paper presents up-to-date results of a project for Vietnamese treebank construction. Since Vietnamese is an isolating language and has no word delimiter, there are many ambiguities in sentence analysis. We systematically applied a lot of linguistic techniques to handle such ambiguities. Annotators are supported by automatic labeling tools and a tree-editor tool. Raw texts are extracted from Tuoi Tre (Youth), an online Vietnamese daily newspaper. The current annotation agreement is around 90 percent.