Objective. This study aimed to develop a scale for evaluating and grading the evidence of prevention and treatment in ancient books of traditional Chinese medicine (TCM), in view of providing a reference for TCM clinicians, supporting the compilation or revision of evidence-based practice guidelines for TCM, improving the level of evidence-based research on ancient TCM books, and supplementing the development of evidence-based ancient TCM books. Methods. The Delphi method was used for consultation among 40 experts in relevant fields. Excel 2016 and SPSS 21.0 were used to analyze the positive coefficient, authority coefficient, degree of concentration, degree of coordination, and degree of expert consensus. Results. In the first round of the questionnaire, a total of 17 evaluation indexes were formulated in three aspects: 5 were deleted, 1 was modified according to the expert opinions, and no additional index was added. In addition, quantitative standards, weight assignment, and grading standards were developed according to the findings of the expert consultation. The positive coefficients of experts in the first and second rounds of questionnaires were 87.5% and 82.9%, respectively. The authority coefficient was 0.835 (> 0.7). The coefficient of variation of the first and second rounds were 0.14 & SIM;0.29 and 0.09 & SIM;0.27, respectively. Kendall's coefficient of concordance of the first and second rounds were 0.135 (p < 0.05) and 0.081 (p < 0.05), respectively. Conclusion. The evaluation indexes and quantitative reference values of the developed scale conform to the characteristics of prevention and treatment evidence in ancient TCM books. It can provide a useful exploration tool for the evaluation and grading of evidences in TCM ancient books.