This research study investigated the students’ and teachers’ perspectives on using the portfolio assessment, which is a new practice in the context of this research study. In China-Mainland, timed-essay exam has been used for writing assessment for a long time; portfolio was introduced recently with a view to improving the assessment quality and help teachers and students improve teaching and learning respectively.The results have suggested that both students and teachers hold positive perspectives on this new portfolio assessment. They have shown their preference on this new practice. From the perspectives of students, portfolio assessment can help them do the self-reflection and their learning behavior could be modified well through this channel. Interviews with classroom teachers also demonstrate the findings from data with students and that teachers would make some modifications as well in their teaching methods and behavior. Nonetheless, the problem on students’ peer feedback in the portfolio should also be taken into consideration because some peer feedbacks are not in good qualities.