Abstract: The genetic diversity and relationships of 18 different Penniseum Rich germplasms were analyzed using Random Amplified Polymorphic DNA（RAPD）markers in order to provide essential information for the development and utilization of Pennisetum germplasm resources. RAPD analysis demonstrated that 19 random primers produced 207 loci， among which 176 were polymorphic loci，the percentage of polymorphic loci was 85%，and each primer produced 6-15 belts. Genetic distance changed from 0.0819 to 1.011，averaged 0.4713；Genetic similarity changed from 0.4907 to 0.9352， averaged 0.6871. According to clustering analysis，we classified the 18 materials into four groups by 0.7，Giant Juncao， P. purpureum×P. americanurn. cv. Reyan No.4，P. purpureum×P. americanurn. cv. Guicao No.1，（P. americanum× P. purpureum）×P. durpureum cv.Guimu No.1，P. purpureum Schum cv. Purple clustered together into one group；P. americanum×P. purpureum and P. purpureum Schum cv. Xijing each formed its own category，while the rest formed one category.