Abstract: In this study,genetic diversity of 22 phenotypic traits of 15 accessions of three ecotypes of medicago ruthenica collected in Inner Mongolia were analyzed by variance analysis,principal component analysis and cluster analysis.The results showed that the variation of phenotypic traits was significant among the tested cultivars,with the largest leaf length and smallest inflorescence length,and the coefficient of variation was 9.67%～56.79%;the cumulative contribution rate of component factors of the first five main characters of 22 phenotypic traits was 89.614%,which reflected the main phenotypic characteristics of 15 species of medicago ruthenica.The plant height,pod length,pod width,leaf shape index,leaf width,floret number,inflorescence pod number and other traits were the main factors that caused the difference of phenotypic characteristics of medicago ruthenica;eucalyptus distance system clustering method was used to divide 15 accessions of medicago ruthenica species into 4 groups.This study revealed the phenotypic genetic diversity of medicago ruthenica,which could provide the basis for the identification,evaluation,conservation,utilization and breeding of medicago ruthenica.