SRAP (Sequence-related amplified polymorphism) and ISSR (Inter simple sequence repeat) molecualr markers were used to evaluate the levels and patterns of genetic diversity among 45 collections of orchardgrass from four continents. Twenty-one primer combinations were used and 480 bands were produced in SRAP, of which 405(84.38%) were polymorphic. On the other hand, twelve primers were used to generate a total of 116 bands in ISSR, of which 116(87.07%) were polymorphic. The coefficient range of genetic similarity was 0.6248-0.9686 and 0.6116-0.9231 respectively. Based on cluster and principal component analysis on the genetic characteristics, all collections could be divided into four groups and five groups in two markers, respectively. According to the analysis of genetic diversity and relationships, the appropriate strategies for collection and conservation of germplasm resources also were discussed and scientific breeding with far genetic relationship materials in orchardgrass were suggested.