Objective To establish an association pattern between symptoms of acute exacerbation of chronic obstructive pulmonary disease（COPD） based on association rules. Methods The data of 1768 patients with acute exacerbation of COPD provided by the survey of 9 provincial-level Chinese medicine hospitals conducted from December 2006 to December 2008 were used and divided into syndrome of lung tightened by wind-cold

syndrome of external cold and internal fluid

syndrome of phlegm-heat obstructing lung

syndrome of phlegm-dampness blocking lung

syndrome of orifices confused by phlegm and syndrome of blood stasis

and the raw data were pre-processed and dataconverted to establish a database based on data mining. The Apriori algorithm was used to select the minimum conditional support degree of 10%

the minimum rule confidence level of 50%

and the maximum number of front items to be 5

to analyze the association rules between the symptoms of each syndrome

and to construct a network diagram between symptoms. Results There were 488 cases of lung tightened by wind-cold syndrome with 13 symptoms and tongue-pulse diagnoses. The top three frequencies of symptoms were cough（98. 57%）

wheezing（83. 81%）

and aversion to cold（72. 34%）

and the cough and wheezing support rate（83. 811%） and confidence（99. 267%）were the highest. There were 388 cases of external cold and internal fluid syndrome with 16 symptoms and tonguepulse diagnosis. The top three frequencies of symptoms were cough（99. 23%）

wheezing（96. 13%）

and aversion to cold（86. 34%）. The highest support for wheezing and cough（86. 911%）

difficult to lie caused by reversed flow of qi and chest congestion were the highest confidence（100%）. There were 1033 cases of phlegm-heat obstructing lung syndrome

which consisted of 14 symptoms and tongue-pulse diagnosis. The top three frequencies of symptoms were cough（99. 23%）

wheezing urgency（88. 19%）

and sputum（79. 57%）; wheezing and cough support（88. 190%） and confidence（99. 561%） were the highest. There were 572 cases of phlegm-dampness blocking lung syndrome with 15 symptoms and tongue-pulse diagnosis. The top three frequencies of symptoms were cough（98. 95%）

sputum foam（88. 81%）

and shortness of breath（86. 88%）; wheezing and shortness of breath（84. 441%） were the highest. The sticky mouth and less eating

poor appetite and less eating

sticky mouth

poor appetite and less eating had highest confidence（100%）. There were 350 cases of orifices confused by phlegm syndrome with 10 symptoms and tongues-pulse diagnosis. The top three frequencies of symptoms were wheezing urgency（87. 71%）

abnormal consciousness（82. 29%）

and throat snoring（73. 71%）

the highest support（73. 714%）was abnormal consciousness and rapid pulse

while the highest confidance（75. 740%） was wheezing and abnormal consciousness. There were 642 cases of blood stasis syndrome with 6 symptoms and tongue-pulse diagnosis. The top three frequencies of symptoms were cyanosis（61. 37%）

tongue ecchymosis（41. 9%）

and sublingual vein distorting（40. 81%）. The support of the purple-dark and sublingual veins was less than 20%

and the confidence was greater than 95%. Conclusion Applying the confidence of association rules can obtain symptom groups closely related to common syndrome symptoms in acute exacerbation of COPD

and construct a correlation model.