To determine the interspecies relationships of 18 Pueraria thomsonii cultivars in molecular level.Eighteen P. thomsonii cultivars were evaluated by using sequence-related amplified polymorphism (SRAP) markers, with P. lobata and P. peduncularis as contrast species. Systematic relationships were constructed based on the UPGMA method by TREECONW software.The results showed that 22 primer pairs produced 338 loci, out of which 216 were polymorphic, the percentage of polymorphic loci was 63.9%. An average of 15.4 loci and 9.8 polymorphic loci were generated by each pair of primers. Genetic distance was analyzed by TREECONW software. Genetic distance of 18 P. thomsonii were changed from 0.004 7 to 0.265 8, with an average of 0.316. Using cluster analysis (UPGMA) based on those polymorphism bands amplified with SRAP primers, the 22 cultivars were classified into three groups, groups 1 with 18 P. thomsonii, group 2 with 3 P. lobata, and group 3 with 1 P. peduncularis. Most of the P. thomsonii from the same region were not in the same group.SRAP markers could be a good marker for genetic relationship research in the P. thomsonii.