To explore research methods for famous physician’s experience through case research of prescription rule of Professor Xu Pengling in treating Pi syndrome. Methods: Three hundred and seven cases of Pi syndrome treated by Prof. Xu were collected and analyzed by TCM inheritance system V2.5 software with associative rules and complex system entropy clustering method to study medicine compatibility. Results: A hundred and thirty-four kinds of common drugs were analyzed and the top ten frequently used medicinal are Cistanche, astragalus, dried ginger, licorice, Ganoderma lucidum, Terminalia chebula, cassia twig, radish seed, Morinda officinalis, Kanekin. These medicinal are warm or even in nature and sweet, pungent or bitter in taste, entering spleen, lung and stomach meridians. The analyzed results, showed that medicinal compatibility are acrid and sweet medicine activating yang, sour-sweet medicine nourishing yin, pungent medicine uprising and bitter medicine dispersing, reinforcing insufficiency and reducing excessiveness and medicine harmonizing liver. Conclusion: Prof. Xu’s treatment thoughts for Pi syndrome are harmony in five tastes, regulation in coldness and heat, tonification and purgation in combination and regulating liver, spleen and stomach, providing reference for methodology of TCM splenico-gastric diseases.