This paper explains the theory of “kidney suffers from dryness and can be moistened by pungent flavor drug”. The view that kidney suffers from dryness in Huangdi Neijing(Inner Canon of Huangdi)can be considered as one of the pathological features of the kidney. It means that kidney fails to transform qi due to deficiency of kidney qi and the fluid cannot be transported and distributed normally,which cause the dryness. The therapy of “moistening with pungent flavor drug” refers to drugs with pungent-flavor and warm-natured can help kidney to transform qi and further promote the transportation and distribution of fluid. Zhang Zhongjing in Eastern Han Dynasty applied Wuling Powder,Shenqi Pill,Gualou Qumai Pill and other recipes. Xu Shuwei and Cheng Wuji in Song and Jin periods discussed the pathogenesis of “kidney suffers from dryness” and the mechanism of “moistening with pungent flavor drug”. You Yi in Qing Dynasty divided the pathogenesis of dryness into the withered yin and coagulated yin. These support the above analysis from the clinical and theoretical aspects.