To gain a holistic understanding of how science teachers dealt with STEM education, this study explored two science teachers’ perceptions and practices at primary schools via the lens of curriculum ideology. By examining their perceptions and practices from six essential aspects (i.e., aim, content, student, teaching, learning, and assessment), we aim to provide deeper insights into what STEM education visions they have, why they promote it, and how they enact it in primary school settings. Combining deductive and inductive approaches, we analyzed data collected from multiple sources, including two rounds of semi-structured interviews, field notes of school visits, artifact like students’ works, and documents like lesson plans and classroom videotapes. Results showed that the two teachers dealt with STEM education differently: one focused on teaching how to think and work as scientists or engineers with a scholar-academic orientation, whereas the other was devoted to laying a foundation for students’ development and future lives with a learner-centered orientation. Based on different value stances and aims, two teachers conceptualize STEM education and translate it into school courses and instructional activities differently, leading to varying degrees of curriculum integration, distinct cognitions of worthwhile content, and different teaching orientations. These findings have implications for researchers and practitioners to comprehend and reflect on how teachers deal with the issues involved in STEM education in school settings. The identified tensions and harmonies between different orientations provide insights into coordinating different values and interests to promote STEM education.