Abstract: The analysis of genetic diversity of phenotypic traits in germplasm resources of old Elymus sibiricus can provide reference for breeding and further study of important traits of E. sibiricus. And, the main phenotypic traits of 39 germplasms of old E. sibiricus were statistically analyzed. The results showed that there were abundant genetic variation in 39 E. sibiricus germplasms, and the coefficient of variation of traits ranged from 8.53% to 41.52%. The genetic variation of spikelet width was 39.95%, and the generalized heritability of 1 000-grain weight was 72.55%. Correlation analysis showed that there was a positive correlation between plant height, stem node number, tassels length and flag leaf length and yield. The first six principal components were extracted by principal component analysis, and their cumulative contribution rate was 78.29%. The 39 E. sibiricus germplasms were divided into 5 groups by cluster analysis. The second group of germplasm could be used as the target parent for breeding high yield with tall plants, large leaves, large spikelet number and large 1 000-grain weight.