Objective: To study the soluble calcium ion content of different compatibility of Baihu Decoction and to discuss the compatibility regularity of Baihu Decoction. Method: ICP-AES was used to detect the content of soluble calcium ion of each single herb and their different compatibility in Baihu Decoction. Result: The results showed that all the herbs in Baihu Decoction contained calcium. Gypsum had the highest content of calcium

followed by Rhizoma Anemarrhenae and Licoroce

Rice had the lowest. The calcium ion dissolution content was increased when Gypsum and Licoroce compatibled together; but not influenced by Gypsum and Rice and reduced by Gypsum and Rhizoma Anemarrhenae. Also the calcium ion content was increased when all herbs of Baihu Decoction presented together. Conclusion: The results reflected the prescription principles of traditional Chinese medicine sufficiently. Gypsum is the monarch drug and Rhizoma Anemarrhenae is the minister drug

both of them have antipyretic effect. Licorice is the assistant drug to restrain some Rhizoma Anemarrhenae’s negative effects on the calcium ion solubility of gypsum

and increase the antipyretic effect of the monarch drug and the minister drug. So the compatibility of traditional Chinese medicine has its own regularity and rationality

it has important guiding significance to the further research on the pharmacological effects of mineral drugs in Chinese herbal compound.