Work placement is defined as a continuing professional development programme aiming at improving vocational teachers' understanding of industry working life through authentic experience. It has been a mandatory programme for all vocational teachers in China since 2016. In this study, we explore the impact of work placement on vocational teachers' practice in school and probe into the factors that facilitate or hinder its impact. The participants were 18 Chinese secondary vocational teachers who were interviewed twice: one week after their work placement and after five months. Six categories of intended and actual changes of teachers' practice were identified, which were grouped into three levels including the school, collegial, and individual classroom practice. Moreover, thirteen facilitating or hindering factors have been clarified, which were divided into three clusters consisting of the teacher characteristics, work placement, and school environment. Limitations and practical implications are discussed.