To clarify the phenotypic variation of oil flax germplasm resources， we evaluated 525 domestic and foreign flax accessions via consecutive two-year field trials. A total of 7 qualitative traits and 17 quantitative traits were investigated for genetic diversity， correlation， principal component， and cluster analyses. The results showed that petal color exhibited the highest genetic diversity index （1.09） among qualitative traits， while stem base shape （0.35） and seed coat color （0.27） showed lower genetic diversity. For quantitative traits， seed weight per plant， number of fruits per plant， and 1000-seed weight presented high coefficients of variation （34.25%， 23.93%， and 20.48%， respectively）， indicating considerable improvement potential. By contrast， capsule diameter （3.37%）， oil content （4.76%）， and protein content （5.92%） had low variation coefficients and represented relatively conservative core traits. Correlation analysis revealed extremely significant positive correlations of 1000-seed weight and seed weight per plant with capsule diameter and oil content， whereas plant height and technical length were extremely significantly negatively correlated with these yield-related traits. Additionally， linolenic acid content was extremely significantly positively correlated with protein content and negatively correlated with oleic acid and stearic acid contents， and both plant height and technical length showed extremely significant positive correlations with protein content. All germplasm were classified into five clusters based on agronomic performance： Cluster I （73 accessions） with superior comprehensive agronomic traits for oil-use breeding； Cluster II （51 early-maturing， high-oil accessions） for high-oil variety development； Cluster III （192 widely sourced and highly variable accessions） for fiber-oil dual-purpose breeding； Cluster IV （108 local germplasm） for gene mining； and Cluster V （101 fiber-type accessions） for fiber flax breeding. Principal component analysis yielded five principal components with a cumulative contribution rate of 73.47%， mainly reflecting yield- and quality-related quantitative traits. Ten elite germplasm including 1962 ROW 210 were finally screened based on comprehensive F-values. This study provides a theoretical basis and technical support for efficient utilization of flax germplasm resources， parental selection， and targeted flax breeding.