Abstract: Using the materials (Paspalum vaginatum Sw.) of three natural populations and one turfgrass cultivar from Guangzhou, Panyu and Zhuhai in Guangdong Province, the genetic diversities and their distribution pattern within and among populations were analyzed by means of RAPD molecular markers. The results showed that a total of 176 reproducible RAPD fragments were produced by using 10-mer random primers, with an average of 8.8 fragments per primer. One hundred and fourteen fragments (64.77% of the total observed) were polymorphic . By analysis of Shannon information index, the genetic diversity indexes within and among populations were 0.023 0 and 0.276 7 respectively, and the genetic diversity index of whole population was 0.299 7. The genetic differentiation coefficient was 0.923 3, which illustrated that total genetic variations among populations was 92.33% and variations within populations was only 7.67% . It also indicate that the inbreeding system of vegetative multiplication of seashore paspalum play an important role in adjusting the genetic variation of this species. UPGMA cluster analysis showed that all individuals from four populations were divided into two clades. One included turfgrass cultivar (Hawaii grass) and population Panyu, and another included population Guangzhou and population Zhuhai. The results are consistent with the morphological characteristics such as height and diameter of culm.