To explore the diversity of flax germplasm resources based on DUS test traits and address the insufficient adaptability of NY/T 2562-2014 Guidelines for testing of distinctness， uniformity and stability of new plant varieties - flax in the Northwest Plateau region， this study employed diversity analysis， correlation analysis， cluster analysis and principal component analysis to investigate the genetic diversity of 285 flax germplasm resources based on DUS test traits and screen regional standard varieties. The results showed that the coefficient of variation for 14 quantitative traits （including initial flowering stage， plant height， etc.） of 285 flax germplasm accessions ranged from 4.91% to 29.55%， and the Shannon-Weaver diversity index varied from 1.021 to 2.073. The Shannon-Weaver diversity index of seven qualitative and pseudo-qualitative traits （such as corolla color and seed coat color， etc. ） ranged from 0.225 to 0.991， indicating rich genetic diversity among the tested flax varieties. Correlation analysis revealed significant synergistic variation relationships among traits of different floral parts， as well as between plant type and technical length. Cluster analysis classified the 285 flax varieties into six groups at a Euclidean distance of 20.13. Group Ⅰ had a high number of capsules per plant； Group Ⅱ featured uniformly white filaments； Group Ⅲ exhibited intermediate phenotypic levels； Group Ⅳ had shorter technical length； Group Ⅴ possessed taller plant height； Group Ⅵ showed lower 1000-kernel weight. Principal component analysis extracted seven principal components with a cumulative contribution rate of 74.502%. Finally， 20 representative flax varieties covering the full phenotypic code variation range of all 285 germplasm accessions were selected. This study provides a new perspective on the identification methods of flax germplasm resources and offers guidance for the regional selection of standard variety in flax DUS testing. In addition， by comparing with the UPOV DUS test guidelines for flax， this paper provides a reference for the revision of the national flax DUS test guidelines of China.