Clarifying the applicability （indications or contraindications） of traditional Chinese medicine （TCM） dietary regimens to different syndromes is a guarantee for the rational application and safety of TCM dietary therapy. By considering evidence from ancient literature， modern research and experts' experience， the Grading System for Syndrome Suitability of Dietary Therapy in TCM （GRADE-SSD） has been constructed. According to the currently available highest-quality evidence， GRADE-SSD classified the applicability of TCM dietary therapy to various TCM syndromes into 2 categories and 4 grades： "definitely" applicable/contradicted （Grade A）， "very likely" applicable/contradicted （Grade B）， "possibly" applicable/contradicted （Grade C）， and insufficient evidence to determine （Grade D）. When applying， first， systematically search the currently available ancient books and clinical research evidence. For different types of evidence （ancient TCM books， randomized controlled trials， observational studies， and meta-analyses）， use the prescribed tools to evaluate the quality of the evidence， and then determine the applicability level of TCM syndromes of dietary therapy based on the principle of "taking the highest" quality. If there is a lack of direct evidence， GRADE-SSD supports a downgraded evaluation based on indirect evidence of "similar prescriptions". When there is a lack of ancient books and clinical research， the GRADE-SSD plan can evaluate the quality of evidence from peer consensus or expert opinions for the applicability level of TCM syndromes of dietary therapy. Based on the requirements for the safety of TCM dietary therapy， when there is both "applicable" and "contradicted" evidence， it should be considered as "contradicted" evidence. GRADE-SSD also provides an evidence certainty update plan based on new evidence in the future. The evaluation results of GRADE-SSD can provide a basis for setting inclusion/exclusion criteria in clinical trials of TCM dietary therapy and stating the applicability of each syndrome in the labels of dietary therapy products.