This study explores the construction of my professional identity during my first year of teaching as a Mandarin teacher in two Australian secondary schools in the Western Sydney Region of NSW. I began teaching in schools in Western Sydney as part of the ROSETE Program, which is an innovative teacher education program in cooperation between the Ningbo Educational Bureau in China, NSW DET in Australia and the University of Western Sydney. Distinct to my experiences in my first year of teaching is that I am Chinese and have only experienced formal education in China. I therefore had no experience of Western conceptualisations of schools, teaching and learning. Auto-ethnography was the methodology used in this study to examine the cultural element of my experiences during the first year of teaching. Data collected and analysed included self-reflective journal entries, teacher interviews, and student surveys. Narratives were developed to identify: the critical incidents I experienced when teaching in the classroom; the factors that contributed to these critical incidents; how I engaged with these critical incidents and how they contributed to my professional identity as a teacher. Aspects of professional identity, beginning teacher and teaching practice theories were used to interpret and discuss these narratives. The aim of the discussion was to make sense of my experience of a Chinese beginning teacher's professional identity transformation in an Australian context. One critical incident I experienced was associated with my lack of familiarity with how Australian students behave in schools. In addition, I lacked experience in managing student behaviour. After a period of teaching practice, I shifted my traditional Chinese beliefs of classroom management to adapt to the Australian classroom context. A second critical incident was my lack of experience with planning and preparing lessons without a fixed and mandatory textbook. A third critical incident was the realisation that my teaching strategies were not helping my students' learning Mandarin. I realised the need to develop my understandings of Western pedagogy to improve the students' learning outcomes. This study contributes knowledge about a non-native, beginning language teacher's experience. This knowledge is important for teachers, for teacher preparation programs and for teacher professional learning in Australia and in China.