Computer supported collaborative writing (CSCW), due to the potential to enhance online collaborative writing performance, has received more and more attention in educational settings in recent years. However, the lack of social presence results in learners not being able to construct group awareness to reduce participation rate and even appear free-riders and suckers. This study thus develops a collaborative writing system with visualization interaction network analysis (CWS-VINA) that can display learners' contribution and interaction relationship through one-mode social network analysis to assist collaborative writing team members in constructing group awareness, facilitate learners' collaborative writing participation behavior, and reduce uneven participation to further promote the learning performance on collaborative writing. With a quasi-experimental design, 50 Grade 8 students of a junior high school in Taipei City were recruited to precede an instruction experiment on collaborative writing. A class of 26 students, as the experimental group, applied CWS-VINA supported collaborative writing, and the other class of 24 students, as the control group, used a collaborative writing system without visualization interaction network analysis (CWS-NVINA). Analytical results show that learners with CWS-VINA supported collaborative writing outperform those with CWS-NVINA on writing performance no matter learners with high or low prior writing ability and high or low CMC competence. Moreover, compared with CWS-NVINA, CWS-VINA provides benefits in promoting learners' overall technology acceptance and perceived usefulness, particularly for learners with low CMC competence. However, there is no significantly statistical difference in promoting the perceived ease of use. According to the interview results, learners indicate that the application of CWS-VINA supported collaborative writing could effectively help them construct group awareness, facilitate team members' communication and coordination, encourage team members to enhance individual contribution, as well as reduce uneven participation.