Peer assessment has been frequently used to improve students' academic writing skills. However, how to address students' unsatisfactory attitude during the peer assessment process remains a major challenge to further improve students' learning outcome and engagement. In our project, we implemented Interactive Peer Assessment, which comprised various components, to improve students' attitude during the peer assessment process. One hundred and fifty-three students participated in the Interactive Peer Assessment on academic writing at a wiki platform. Data were collected from student questionnaires and the records in webpages of wiki platform. It was found that the students demonstrated different levels of attitude changes in the form of compliance, identification and internalisation, and that different attitude changes were elicited by various components of the Interactive Peer Assessment. Significant learning improvement was also found in students' academic writing skills. Results of this study demonstrate the value and importance of incorporating strategies planned specifically to foster and maintain a positive attitude in the peer assessment process so as to enhance the desired effectiveness of peer assessment on learning outcomes and engagement.