Generally, collaborative writing involves almost the whole activity of writing. Meanwhile, collaborative writing is also an important mode in English teaching, which has attracted great attention around researchers. Research on collaborative writing cannot only provide useful instruction for English teaching, but also can contribute to the studies of second language acquisition. However, current studies on collaborative writing mainly focused on the comparison between different writing modes by means of experiments in the classroom without consideration of the contexts outside the classroom and any discussion of the teaching effect of collaborative writing. This paper aims to examine the activities involved in collaborative writing in pairs in the course “Academic Writing” and 9 graduate students’ perceptions of them. The author conducted semi-structured interviews to collect data and analyzed the interview data with thematic analysis. The study shows that there are mainly three types of collaborative writing activities: writing in pairs, in small groups and individually. Students’ perceptions of the collaborative writing can be put into three categories: some students strongly supported it; some opposed it; while others thought it made no difference. This study can contribute to the understanding of collaborative writing in Chinese contexts.