Previous research concerning teacher practical knowledge has revealed its epistemological foundations, content structure and research methodology, but little research examines its ethical dimension. Based on a four-year project in China, this study probes the ethical dimension of an experienced teacher's practical knowledge, explicated in a dilemmatic but teachable moment. Narrative inquiry is used as both a research method and a representational form to reveal the teacher's ethical decisions and actions in the nested macro-meso-micro dilemmatic spaces. It is found that the teacher's practical knowledge is embedded in a complicated web of meanings, and tapestried by her compromise to the national policies, her negotiation with the school governance and her caring for her students with diverse backgrounds. The ethical dimension of her practical knowledge provides her a vital power to carry out her educational practice. It is advocated that an "ethical turn" for research and practice in teacher professional development is needed, so as to authorize teachers' professionality reflected in their roles as humanity cultivators and transformative intellectuals. Moreover, under the global educational reform context since late 1990s, this article can be seen not only as a case from China, but also has implications for other countries in the world.