Portfolios are the records of learning process, providing evidences of experiential learning. It can be a valuable tool not only for understanding the learning process but also for evaluating the accomplishment. Portfolios promote learners to reflecting, thinking, improving in learning as well as achieving learning goals. It has been widely applied in medical education. The goals of resident training outcomes in Wan-Fang Hospital are the ACGME six core competences. The Wan-Fang hospital, one of Taipei Medical University affiliated hospitals and the first implementing portfolio assessment teaching hospitals in Taiwan, will conduct portfolio assessment to assess residents competences. Facilitating residents bring reflective learning into practice, personal and professional growth and demonstrating the outcomes of training program. This study describes initiating and implementing portfolio assessment procedures. Qualitative and quantitative research methods are applied for evaluating the portfolio assessment process and the data of validity and reliability. Qualitative data collection methods of interview, focus groups and meetings will be used understanding the experiences and viewpoints of residents, mentors and assessors. Then quantitative data collection method of questionnaire will be subsequently used. The results of this study will provide experiences and suggestions for the implementation of portfolio assessment system in medical education.