Objective : This study will analyze the constitution of Danxihuqianwan(丹溪虎潛丸) with the dragon-tiger and lead-mercury theory of Su Shi(蘇軾). It would help understand more the usage of Danxihuqianwan over the scope of Sa-nam and bo-buk(瀉南補北) theory that has been well known until now. Methods : This study tried to analyze the explanation about Danxihuqianwan in Yixuerumen(醫學入門) that had used the dragon-tiger and lead-mercury concept with the theory of this kind that appears in Sushenliangfang(蘇沈良方). Results & Conclusion: Based on the internal alchemy theory, Su Shi proclaimed that dragon[龍] corresponds to mercury[汞] Jeong(精) Hyul(血), and tiger[虎] corresponds to lead[鉛] Qi(氣). It is said to be in good position that dragon appears from fire and tiger is hidden in water. Su Shi also expalined the relation between dragon and tiger as the relation of water[水] and fire[火] between heart and kidney. As Li Yan(李?) did, the dragon-tiger theory could be applied to the analysis about Danxihuqianwan, and it explains well the effect of this prescription that makes tiger hidden in water and thus help cure the diseases such as atrophy syndrome.