Objective By excavating the association rules about CAP’s common syndrome elements of the disease location and nature combined phlegm syndrome elements， to found the combined features about CAP’s common syndrome elements of the disease location and nature combined phlegm syndrome elements. Methods Four diagnostic information of 201 cases with Community-acquired Pneumonia were collected. A database based on the data of CAP’s common syndrome elements of disease location and nature combined phlegm syndrome elements were established. The association rules were excavated by the method of Apriori Algorithm and the combined features of CAP’s common syndrome elements of the disease location and nature combined phlegm syndrome elements were analyzed. Results 16 rules were concluded and 9 rules were left by eliminating repetitive. Conclusion The features of CAP’s common syndrome elements combined phlegm syndrome elements can be mined by association rules analysis， which is useful for the recognition of combined features of syndrome element of Community-acquired Pneumonia， and offer a reference for clinical diagnosis and treatment of community-acquired pneumonia.