Corpora present a basic informational source for varied NLP applications. Their construction becomes now days necessary. This paper presents a tool created to help syntactic tagging an Arabic Treebank. It is based on an already constructed grammar called ArabTAG which constitutes a representational method of Arabic grammatical rules using TAG formalism. This tagging tool is a node among a set of other pre-treatment steps as: morpho-syntactic analysis, grammatical tagging and sentence segmentation. It gets as input a sentence and helps to give it the appropriate syntactic tree in an incremental manner.