Competency among medical teachers on undergraduate education is essential to meet the growing needs of medical education, but less is known about what competencies the medical teachers need. The aim of this study was to develop a scale to describe teaching competencies for medical teachers in China. The Delphi method was used to select competency items, and the Precedence Chart was used to determine the weight of each item. We enrolled 39 experts from a top Chinese medical university, and three rounds of ratings were conducted before reaching consensus. The developed 36-item competency scale consisted of four themes that were regarded as essential, including teaching attitude (nine items), teaching process (18 items), teaching effectiveness (five items), and teaching-related research (four items). The experts rated more than four (out of five) in terms of the scale's comprehensiveness, scientific rigour, and feasibility. The scale has great potential to guide faculty development.