Aegilops tauschii Ais a wild relative of common wheat(Triticum aestivum) and acts as an important resource of elite genes including genes for resistance to biotic and abiotic stresses. To improve the cadmium(Cd) tolerance of wheat varieties using A. tauschii resources, we investigated the genetic variation of biomass-based Cd tolerance in 235 A. tauschii accessions treated with 0(control) and100 μmol L-1CdC l2(as Cd stress). Simultaneously, we performed a genomewide association study(GWAS) using a single-nucleotide polymorphism chip containing 7185 markers. Six markers were found to be significantly associated with Cd tolerance by a general linear model and a mixed linear model. These markers were close to several candidate/flanking genes associated with Cd tolerance according to results in public databases, including pdil5-1, Acc-1, DME-5A,TaA P2-D, TaA P2-B, Vrn-B1, and FtsH-like protein gene. The A. tauschii accessions were classified as high, moderate, and low Cd-tolerant according to a secondary index, the synthetic index(SI), in proportions of 9%, 57%, and 34%, respectively. By the average SI, accessions from Afghanistan,Turkey, Azerbaijan, and Iran showed relatively high Cd tolerance. Aegilops tauschii Ais a wild relative of common wheat (Triticum aestivum) and acts as an important resource of elite genes including genes for resistance to biotic and abiotic stresses. To improve the cadmium (Cd) tolerance of wheat varieties using A. tauschii resources, we investigated the genetic variation of biomass-based Cd tolerance in 235 A. tauschii accessions treated with 0 (control) and 100 μmol L-1CdC12 (as Cd stress). Simultaneously, we performed a genomewide association study (GWAS) using a single-nucleotide Polymorphic chip containing 7185 markers. Six markers were found to be significantly associated with Cd tolerance by a general linear model and a mixed linear model. These markers were close to several candidates / flanking genes associated with Cd tolerance according to results in public databases, including pdil5-1, Acc-1, DME-5A, TaA P2-D, TaA P2-B, Vrn-B1, and FtsH-like protein genes. The A. tauschii accessions were classified as high, moderate, and low Cd-tolerant accordin g to a secondary index, the synthetic index (SI), in proportions of 9%, 57%, and 34%, respectively. By the average SI, accessions from Afghanistan, Turkey, Azerbaijan, and Iran showed relatively high Cd tolerance.