In recent years, STEM learning has become a new education initiative worldwide. However, little research has considered the needs of students with Intellectual Disabilities (ID) in this initiative. Believing that individuals with disabilities should be evaluated and defined by their capacity, strengths, and broad range of interests and abilities, this research investigated this less-explored perspective in STEM learning, namely supporting teachers providing STEM learning for ID students. Four teachers in two special schools for children with intellectual disabilities worked collaboratively with each other in their schools to plan and implement STEM learning. Peer coaching was recommended to the teachers in order to improve their planning of STEM learning and their teaching practices for teachers' professional development (TPD). The qualitative research methodology was used, and detailed analysis of teachers' pre- and post-TPD interviews and reflections to identify good practices that helped ID students accomplish the tasks and disparities that influenced peer coaching was performed. While challenging, with support from peers and due considerations of the special learning needs of ID students, this research provides useful insights for teachers to support ID students in STEM learning, including the use of technology in the STEM learning design, the consideration of inquiry learning based on students' abilities in implementation, and the focus on teachers' disparity and school involvement with peer coaching.