Compared to studies focusing on the views of school counselors, few studies explored the interdisciplinary collaboration in relation to school guidance from the perspective of homeroom teachers. Since homeroom teachers play an important role in school guidance work, From the perspective of homeroom teachers, the study aims to explore how homeroom teachers conduct school guidance work with different professional paradigms, how their guidance practice works, and how different they are between homeroom teachers and counsellors. The intention is in an attempt to clarify how the homeroom teachers’ viewpoint and their practice possibly impact guidance work or interdisciplinary collaboration. In total, five secondary school homeroom teachers were interviewed in a semi-structured method. The interviews were recorded, transcribed, and then further analyzed based on the principles of grounded theory. The results revealed four aspects with respect to interdisciplinary collaboration on school guidance work valued by homeroom teachers, which are summarized as follows: (1) the role differences between homeroom teachers and school counselors in terms of conducting school guidance work; (2) the different manifestation of student clients shown in front of homeroom teachers and school counselors; (3) the differences between student-homeroom teacher and student-counselor relationships; (4) homeroom teachers’ advantages and disadvantages in terms of conducting school guidance work. This study suggests that the homeroom teacher’s professional paradigm is different from that of school counselor, and students behave differently in front of homeroom teachers and school counselors respectively. Accordingly, how to conduct clarification and discussion for the purpose of reaching a consensus on interdisciplinary collaboration is the priority for both homeroom teachers and school counselors before launching school guidance work for student clients.