The construction of syntactic tree structures is vital to different Natural Language Processing applications. In the meanwhile, the use of monolingual or bilingual structures directly affects the quality of Machine Translation systems. However, manually annotated syntactic tree structures are not only considered as a time consuming task but also a very expensive work, and automatic construction approaches cannot always guarantee the quality of the syntactic trees. In this paper, a system for annotating and constructing synchronous grammar tree structures in a semi-automatic way is proposed. The system is built in the Web environment with a graphical display for users to review and modify alignment relationships between nodes of the tree and strings or trees of the other language. The core part relies on the parsing of Constraint Synchronous Grammar, and consists of several modules in establishing alignments at different levels between the languages, including relationships between syntactic tree and strings of the other language, and bilingual tree alignments. Moreover, it provides import functions in obtaining monolingual skeletal bracketing syntactic tree and Translation Corresponding Tree structures for the creation of synchronous rules in order to have wider applicability. © (2013) Trans Tech Publications, Switzerland.