In light of the fact that technology teachers' understandings of the nature of technology (NoT) determine students' perceptions of NoT, this study turned attention to technology teachers, and developed a comprehensive theoretical instrument for assessing their understandings of NoT. The theoretical framework of NoT was proposed using a theory-based explanation informed by the philosophy of technology (PoT), historical, sociological and educational literature. The eight dimensions were as follows: 'technology as object', 'technology as knowledge', 'technology as activity', 'technology as volition', 'history of technology', 'the role of technology in society', 'the relationship between science and technology', and 'technology as a double-edged sword'. Eight international experts were invited to review the content validity of the NoT scale, and 835 valid questionnaires answered by Chinese high school general technology teachers were used to test the reliability and convergent validity of the scale. The results showed that the NoT scale had a high reliability and good validity, which could be used to measure and assess technology teachers' understandings of NoT. The development of the NoT scale provided a new perspective for interpreting NoT, and helped technology teachers consider how to more effectively transfer their understandings of NoT to students.