Syndrome diagnosis in Traditional Chinese Medicine (TCM) holistically evaluates functional and energetic imbalances in the body. This review aims to examine the fundamental principles of syndrome diagnosis in TCM by integrating meridian theory, the eight extraordinary vessels, and the five-element theory within a holistic diagnostic framework. The conceptual and theoretical foundations of syndrome diagnosis were examined by focusing on the functions of the meridian system, the regulatory roles of the eight extraordinary vessels, and the generating and controlling relationships among the five elements. The significance of these systems in interpreting energetic imbalances and inter-organ relationships was evaluated from a holistic perspective. The findings indicate that meridians are considered functional pathways that facilitate the circulation of Qi and blood and establish connections among internal organs, organ systems, and musculoskeletal structures. Clinical manifestations are interpreted according to patterns of imbalance along the meridians rather than solely on the basis of individual organ pathologies. Among the eight extraordinary vessels, Du Mai, Ren Mai, and Chong Mai are particularly important in evaluating reproductive and gynecological conditions, including infertility, menstrual irregularities, and menopausal symptoms. The five-element theory contributes to syndrome differentiation by explaining functional relationships among Wood, Fire, Earth, Metal, and Water through generating and controlling cycles. The integrated evaluation of these three theoretical systems provides a multidimensional framework for identifying patterns of disharmony and understanding energetic balance and functional relationships within the body. In conclusion, this integrated approach supports holistic syndrome diagnosis and facilitates the determination of individualized treatment strategies in TCM.