Safflower (Carthamus tinotorius L.), which serves as an important oil crop, contains higher content of the unsaturated fatty acids. Forty-eight SSR markers were used to unlock the genetic diversity and the population structure of 74 safflower germplasm resources from 27 countries. The association analysis using the general linear model (GLM) and the mixed linear model (MLM) was conducted to identify the molecular markers associated with oil-related traits. The results showed that the polymorphism information content (PIC) value ranged from 0.0632 to 0.3750, with an average of 0.2937, and the genetic diversity index ranged from 0.0653 to 0.5000, with an average of 0.3700. The cluster analysis using UPGMA assigned 74 safflowers into 3 groups, including 7, 52 and 15 genotypes, respectively. The population structure analysis suggested three subgroups consisting of 7, 55 and 12 genotypes, respectively. At a significant level of p < 0.05, 18 markers associated with oil-related traits were detected by either GLM or MLM models, which explained the phenotypic variation with a range of 5.42 % to 20.69 % and 4.35 % to 20.69 %, respectively. Out of that, twenty eighteen markers, except for Ct589 and Ct178, were detected by both approaches. Taken together, this study suggested an abundant genetic diversity and revealed several markers associating with oil-related traits, which provided the marker resource in future breeding for high-oil content safflower.