This study investigated the epistemological beliefs of physics and mathematics held by a group of college students in Taiwan, and explored how they interpret the relationship between the two disciplines. Participants’ beliefs were examined via open-ended questionnaires and semi-structured interviews. This study also conducted a historical review of the interrelationship between physics and mathematics and took experts’ beliefs of physics and mathematics into account in order to establish a reference base for interpreting the participating college students’ beliefs. The findings indicated that these college students held moderate epistemological beliefs about physics and mathematics in some sense, but lacked critical thinking in how to deal with potential conflicts among several issues. They were ignorant of social and cultural factors, and disregarded the role of philosophical beliefs, showed insufficient knowledge about the role of creativity and imagination, and lacked a realization of organic interactions between physics and mathematics. It was further revealed that beliefs about mathematics may play a role in students’ tendencies toward learning physics. Having interdisciplinary experiences in physics and mathematics could not only help students develop sophisticated understandings of the dynamic nature of physics and mathematics, but could also encourage them to understand the two related subjects in a meaningful way. Considering that beliefs are culturally bound, it is essential for future research to focus on diverse settings and cultural backgrounds by means of an integrated methodology to identify students’ epistemological beliefs of physics and mathematics.