This study focused on 194 Agropyron cristatum （crested wheatgrass） germplasm resources from diverse geographic origins. To assess phenotypic diversity and screen elite germplasm， we employed a suite of analytical methods including coefficient of variation （CV）， genetic diversity index， cluster analysis， principal component analysis （PCA）， correlation analysis， and grey relational analysis， based on 28 key phenotypic traits. Additionally， we used QGA software to analyze genetic distance， sampling proportion， and clustering methodologies， aiming to identify the optimal strategy for constructing a core germplasm collection. The reliability and representativeness of the resulting core set were rigorously verified. The results demonstrated that：statistical analysis of 28 phenotypic traits in 194 accessions of Agropyron cristatum （crested wheatgrass） revealed substantial phenotypic variation. The coefficient of variation （CV） ranged from 17.02%-87.85%， and the genetic diversity index （Shannon-Wiener index， H'） varied from 0.500-2.103. For qualitative traits （e.g.， spike shape， glume color）， the CV spanned 24.43%-52.75%， with an average H' of 0.869—indicating moderate diversity. For quantitative traits （e.g.， plant height， spike length）， the CV was broader （17.02%-87.85%）， and all H' values exceeded 1.524 （average： 1.962）， which reflected high genetic diversity. The results demonstrated that A. cristatum possesses rich genetic diversity， providing a solid foundation for elite germplasm selection and breeding programs.The grey relational analysis （GRA） demonstrated that spike length， spike width， spikelet number， length of the first rachis internode， spikelet color， flag leaf width， leaf sheath length， plant color， and other morphological traits served as key indicators for the comprehensive evaluation of Agropyron cristatum （L.） Gaertn. germplasm resources. A set of elite germplasm accessions （B61， B1， B37， B83， B164， B193， B48， and B85） were identified through screening. All of the accessions are incorporated into the core collection， thereby providing a scientific basis for the construction of a representative core germplasm set. Multivariate analysis integrating principal component analysis and QGA software optimization demonstrated that the combination of Euclidean distance metrics， multiple clustering priority sampling， single linkage method with a 25% sampling proportion constituted the optimal strategy for core germplasm construction in Agropyron cristatum （L.） Gaertn. （MD=0%， CR=100%， VD=25%， VR=113.474%）. The resultant core collection comprising 48 accessions exhibited a significantly higher cumulative contribution rate （75.54%） compared to the original population ， while maintaining 100% of the original genetic diversity. This scientifically validated core set provides a robust foundation for germplasm utilization and genetic improvement in crested wheatgrass.

Agropyron cristatum （crested wheatgrass）  /  Phenotypic traits  /  Genetic diversity  /  Core germplasm  /  Comprehensive evaluation