This study aims to investigate the impact of co-design process on ex-mentally ill persons practicing expressive textile arts after taking a series of co-design textile arts and fashion creativity workshops from service learning subject, “Community Engagement through Expressive Textile Arts and Fashion” offered by the Hong Kong Polytechnic University from 2017 to 2018. A total of 38 prototypes had been jointly created by exmentally ill persons, subject lecturers and undergraduate students during attending the co-design workshops in these two years. Through the co-design process, expressive textile arts and fashion creativity was adopted as the caring medium to improve ex-mentally ill persons’ mental well-being, socialhealth, empowerment, self-esteem, self-understanding and self-confidence, and also rebuild their personal identity. Concepts of ex-mentally ill persons in the community, expressive arts therapy, textile arts, expressive textile arts and service-learning subject are introduced. In this study, quantitative research method was used to explore the impacts of co-design process on ex-mentally ill persons practicing expressive textile arts. For the results, positive impacts are found on ex-mentally ill persons of feelings and thoughts before and during attending the expressive textile arts workshops in 2017 and 2018. And the most important impact is raising public awareness, it helps to eliminate misconception of ex-mentally ill persons in the society, reduce alienation and discrimination, and also promote social cohesion and acceptance.