English immersion teaching approach has gradually gained its popularity in China since the CCUEI Program was introduced to China, which posed a great demand for qualified English immersion teachers. At the same time, there is a pressing need for in-service teachers to sustain their professional development. This study aims to provide a complete picture of English immersion teachers’ preparation and professional development in a private school in Macao, in order to find 1) how the previous knowledge and training influenced the teachers and how the school has chosen their immersion teachers; 2) how immersion teachers in the school effectively manage their class; what specific strategies they have adopted to implement immersion; 3) how the teachers in the school maintain professional development while teaching full-time; how the school policies influence immersion teachers’ professional development; how the teachers themselves sustain their professional growth. By analyzing data collected from the case school, the author of this paper has found that the school values the English proficiency of immersion teachers and their exposure to western culture. It also cherishes the pre-primary and primary education background of the teachers. The school also believes that Chinese teachers of English are more qualified to teach Chinese students because they understand their students as well as their needs, better. Also, an early partial English immersion teacher in China not only needs to possess the qualities mentioned above, but are also required to develop unique strategies such as natural and fluent body language, the ability to create English context within the school, and the use of multiple instructional methods and activities in the classroom. v To promote the professional development of the immersion teachers, the school has adopted some strategies which have effectively boosted the professional development of the teachers , including: 1) hosting CCUEI conference; 2) organizing visits to other immersion model schools; 3) attending workshops; 4) receiving external support from experts and universities; 5) organizing open classes; 6) offering management support. Also, by building teacher support groups, reflecting on their teaching, and peer sharing, the teachers in this school have successfully maintained their professional growth. The study offers educational insights to English immersion teacher education in China, and also contributes to the enrichment of immersion teacher education and professional development research. Meanwhile, it can provide some inspirations to both novice and in-service English immersion teachers. Moreover, it offers general immersion education situation in both Chinese mainland and Macao. Key words: early partial English immersion teacher preparation; case study professional development.