Objective To analyze the composing principles of the traditional Chinese medicine (TCM) prescriptions for eczema by data mining methods.Methods The CNKI,VIP,Wanfang and SinoMed from inception to the December 31st 2016 were searched,which were collected into the traditional Chinese medicine inheritance support system (TCMISS) and analyzed by data mining methods,which included frequency analysis,Cluster Analysis and correlation rules.Results Based on the analysis of 51 cases of TCM prescriptions reported in literatures,16 herbs (frequency≥8) were found frequently used.And the results showed that 22 combination herbs (supporting coefficient=8),4 association rules (supporting coefficient=8 and confidence coefficient=0.8),7 core combinations and 1 new TCM prescription were found.Conclusions The TCM prescriptions for eczema are mainly composed of herbs with heat-clearing effect,especially with damp-drying effect,supplemented by herbs with blood-nourishing,blood-cooling and rheumatism effects.