The research focuses on investigating the development of university students’ writing ability in academic discourse in English. In the research, students’ English language writing ability is evaluated in terms of linguistic features which are objective and measurable, covering language formality, language complexity, and objectivity. The linguistic features are located at the lexicogrammatical level (for example, the occurrence of nominalization, attributive adjective, abbreviated forms etc.) and at the discourse level (relation of clauses). The data for the present study consists of the written work produced by the students who participated in the Language Companion Course (LCC) project carried out at City University of Hong Kong. The grammatical indicators denoting academic discourse in their writings are identified qualitatively and quantitatively. An evaluation matrix is established based on the features to optimize the analysis to allow comparison between courses, assignments, and versions. The results show that students have demonstrated improvement across versions and assignments in terms of grammatical accuracy, and slight improvement in the achievement on producing academic writing.