Determining the weight of diagnostic indicators in Criteria for Traditional Chinese Medicine (TCM) Syndrome to achieve the quantitative diagnosis of syndrome in TCM was one of the key steps in the development of syndrome differentiation Criteria. Analytic Hierarchy Process (AHP) was introduced and applied into research of determining the weight of diagnostic indicators in criteria for TCM syndrome early by our research group. In this paper, the applicability of AHP in the construction of dialectical criteria was discussed theoretically, and the improvement of AHP survey method and questionnaire was introduced in detail. Practice had showed that the improved AHP was more operable and the quality of investigation was further improved. AHP could be used as a stable and effective method to determine the weight of diagnostic indicators in criteria for TCM syndrome. Besides, AHP was worthy of further popularization and application in clinical and scientific research.