Teachers' digital teaching competence is a prerequisite for efficient teaching. This study aimed to develop a scale to assess primary and secondary teachers' digital teaching competence (PSTDTC). We analyzed and generalized definitions, models, and frameworks for PSTDTC, proposed a five-dimension model (digital teaching design competence, digital teaching implementation competence, digital teaching evaluation competence, digital teaching responsibility, and digital teaching attitude), and developed a scale. Three specialists and seven in-service teachers tested the content validity of the PSTDTC scale. An exploratory factor analysis (n = 473) revealed a 5-factor structure corresponding to the theoretical model. Confirmatory factor analysis (n = 574) was used to assess the structural validity of the final scale. Other statistical findings indicate that the scale is scientific and reliable. In the study, we also used latent class analysis (LCA) to identify unobserved structures and the subpopulations of teachers. According to the LCA results, three latent classes were obtained, including low-level, intermediate- and high-level digital teaching competence. Through multiple logistic regression, we discovered that urban and secondary teachers are more likely to enter intermediate- and high-level digital teaching competence classes. Therefore, the PSTDTC scale provides educators and researchers an effective diagnostic instrument for evaluating the present state of teachers' digital teaching.