Based on the natures and flavors of herbal medicinals recorded in

Shen Nong's Classic of the Materia Medica

（《神农本草经》）；

Miscellaneous Records of Famous Physicians

（《名医别录》）， this study analyzed the characte-ristics of the natures， flavors and combination of medicinals of the two-herb compound formulas in

Treatise on Cold Damage and Miscellaneous Diseases

（《伤寒杂病论》）.Finally， 31 compound formulas were included， and it was found that the nature and flavor of the herbs in these two-herb compound formulas are closely related to the functions of the compound formulas， such as the common pairing of the acrid and the sweet herbs to warm

yang

and transform

qi

， the acrid and the bitter herbs in pairs to regulate and harmonize cold and heat， the sweet and the bitter in pairs to remove dampness and clear heat， the acrid and the acrid in pairs to arrest vomiting and direct

qi

downward， and the sour and the sweet in pairs to slow the urgent and relieve pain. Regardless of the deficiency or excess nature of the disease， the corresponding two-herb compound formulas often aim to reinforce healthy

qi

while eliminating pathogenic factors， with some formulas showcasing a unique correspondence between the disease pattern and the symptoms addressed.