Abstract:The genetic diversity of 215 individuals of Miscanthus floridulus from 13 natural populations distributed in Guangdong Province was investigated by using intersimple sequence repeat (ISSR) techniques. A total of 81 unambiguous and repetitious bands were scored by 9 primers. The results showed that the genetic diversity of M. floridulus was high, at species level, percentage of polymorphic loci (PPB) was 93.83%, Nei's gene diversity (He) for 0.3969, and Shannon's information index (Hsp) for 0.5724; while at population level, PPB=81.91%, He=0.3015 and Shannon's information index (Hpop)=0.4460. The coefficient of genetic differentiation among populations (Gst) was 0.2379, and gene flow among populations (Nm) was 1.6018. The AMOVA analysis showed that 79.56% of the total genetic variation within populations and the rest (20.44%) partitioned among populations. No significant correlation was found between geographical and genetic distance (r=-0.2811, P=0.9590).