Abstract: Genetic differences of 28 Cynodon dactylon populations were examined by RAPD and morphological observation. Using 20 ologonucleotide primers, 326 bands were obtained of which 314 (96.32%) were polymorphic, an average of 15.7 per primer. A complicated genetic background and abundant genetic diversity were found in the experimental germplasms. According to cluster and morphological analysis, the 28 C. dactylon populations could be classified into three types of which type A (12 populations) had a genetic similarity coefficient ranging between 0.251 0 and 0.054 1. The comparative genetic differences of this type were larger with more abundant polymorphisms than the other types. The leaves of type A were long and wide with a hard texture. This type included germplasms from Guangzhou, Zhejiang, Wuxi, Nanjing, Qingdao. Type B involved 9 populations with a genetic similarity coefficient of 0.233 9-0.121 6. The genetic difference was less and genetic relationship closer than in type A. The leaves were shorter and the texture finer. Type B included varieties introduced from other cities and other countries. Type C consisted of 7 populations collected from interland regions of Shandong province. They had a genetic similarity coefficient of 0.500-0.143 showing a large genetic difference.