Abstract: Kentucky bluegrass （Poa pratensis L.）is a hardy, persistent forage and turf grass adapted to a wide range of soils and climates. Its ever-increasing adoption in highly cared-for sports fields has attracted the attention of many seed companies. However in the past, the breeding of superior varieties was often hampered by the extreme complexity of the genome. The polymorphism is important for broading the genetic base and may be exploited via heterosis. The genetic relationship of 16 bluegrass cultivars, including 15 accessions Kentucky bluegrass cultivars and 1 entries Canada bluegrass ( Poa compressa L. ) cultivars from different breeding company were analyzed using 25 RAPD markers. 25 RAPD primers generated 218 bands, of which 196 bands （89.91％）were polymorphism. It showed that the Canada Bluegrass was separated from other Kentucky Bluegrass and genetic polymorphism in the Kentucky Bluegrass cultivars was low, the coefficient among the cultivars fell between 66%~98%. Dendrogram obtained using these molecular markers were partly in agreement with their separated morphologic character. Cultivars from the same company were not clustered in one group. The breeding method of bluegrass was discussed.