Abstract： This article introduces YAO Zhiling's clinical experience in applying Huanglian Wendan Decoction based on YAO's lesser yang theory. Huanglian Wendan Decoction is derived from Wendan Decoction and has been widely used by many physicians from the perspective of "phlegm-fire." In clinical practice，YAO Zhiling，based on the "YAO's six meridians" syndrome differentiation method， employs Huanglian Wendan Decoction as the primary prescription for "improper lifestyle leading to wind-damp stagnation and heat， or the generation of turbidity， toxins， and stasis，all stagnating in the lesser yang." She emphasizes that the disease location is in the lesser yang meridian， with the core pathogenesis being "stagnation." After flexibly modifying the prescription，YAO Zhiling applies it with the method of "pungent-opening and bitter-descending， dispersing and draining pathogens from triple energizer， and clearing heat to resolve dampness" to treat various internal miscellaneous and stubborn diseases，forming a unique and standardized system of theory，methods，prescriptions，and herbs.