Objective: To study the compatibility and therapeutical basis of composite herbal medicines of Lingguishugan Decoction(LD)(Poria, Ramulus Cinnamomi, Rhizoma Atractylodis Macrocephalae, Radix Glycyrrhizae.)Methods: Ethanol extract test solutions of the different combinations were prepared according to the orthogonal layout L 16 (4 5). Pharmacologic experiments, such as the time of survival of mice in shortage of oxygen in normal pressure, the antagonistic effect on arrhythmia induced by chloroform and the diuretic effect were carried out with LD. Variance analysis, canonical correlation and stepwise regression analysis were applied to interelationship between the amount of each drug and the pharmacologic data. Then, the fingerprints of the solutions were tested by HPLC method and 50 chromatographic peaks were obtained. Correlation and regression analysis was applied to interelationship between the area of each peaks and the pharmacologic data.Results: The results confirmed the poria and cinnamon twig are the basis, while ovate atractylodes and licorice are the adjuvans. 17 peaks, which were established as the therapeutical basis of the decoction, were selected from all compounds, and cinnamic acid of cinnamomum cassia, glycyrrhizin of Glycyrrhiza uralensis and dehydrotumulosic acid of Poria cocos were selected as the markers to evaluate the quality of the decoction.Conclusion: This study provided a significant try of studying the compatibility of composite herbal medicines.