Genetic variation and relationship of 53 accessions of D. glomerata collected from 5 continents were analyzed using simple sequence repeat (SSR) molecular markers with 15 SSR primer pairs. The following results were obtained. (1) A total of 127 alleles were detected at 15 loci. The number of alleles per locus ranged from 5 to 12, with an average of 8.5. The rate of polymorphic sites (P) was 95.21%; the polymorphic information content (PIC) ranged from 0.30(A04C24)to 0.44(A01F24) with an average of 0.36. (2) The genetic similarity (GS) among all accessions ranged from 0.43 to 0.94, for all geographical groups GS ranged from 0.73 to 0.91, and high genetic diversity was observed in Asia (P, 90.55%) and Europe (P, 86.61%) groups. These results suggested that there was rich genetic diversity among all orchardgrass accessions tested. (3) Based on the cluster and principal component analyses, 53 accessions could be divided into five groups according to the nearest phylogenetic relationship, and accessions from the same continent were classified into the same group associated with their geographical distributions.