Objective To study on the experts’ cognition homoplasy on the common characteristics of "Du-pathogen" in TCM.Methods The questionnaire survey was carried out to 110 highly titled experts in different specialties from 9 different areas with the "Expert Questionnaire" about the characteristics of "Du-pathogen" in TCM based on the previous researches. First

reliability and validity test on all the terms of pathogen were made for descriptive statistics of recognition; then they were classified through cluster analysis and factorial analysis; finally

the characteristics of pathogen were taken as independent variable and "the excessive pathogen damaging the health" was taken as dependent variable for a Logistic regression analysis to explore the correlation between the characteristics of pathogen and this understanding for finding roughly out the consensus of experts.Results The recognition of experts on the 8 characteristics of Du-pathogen （fierceness

cruelty

vital qi damaging

dirtiness

meridians and collaterals damaging

accompanying

multi-damaging

changing with conditions） was above 84%. After internal confidence analysis and structure validity test

the Koruna Bach coefficient was >0.7

factor technical contribution rate was >70%. The cluster analysis and factorial analysis showed that the fierceness

cruelty

and vital qi damaging were often clustered with each other and constituted the factors of main characteristics of Du-pathogen. In the Logistic regression analysis

it was discovered that fierceness

cruelty

and multi-damaging were closely related with the recognition of "the excessive pathogen damaging the health" （P<0.05）.Conclusion The main characteristics of pathogen are fierceness

cruelty

and vital qi damaging. The recognition of "the excessive pathogen damaging the health" reveals the common characteristics of Du-pathogen to a certain degree.