Abstract: In order to characterize the genetic relationship of the geographic populations of Sitobion avenae (Hemiptera: Aphididae)in China, a 588 bp region of the mitochondrial cytochrome oxidase subunit I (mtDNA-COI) gene was sequenced andanalyzed among the different geographic populations. 269 individuals were collected from 17 localities in different wheatgrowingareas in China that covered most of the range reported for this species. Within the sequence among thesegeographic populations, 15 polymorphic sites defined 16 distinct haplotypes, ranging in sequence divergence from 0.2%(one nucleotide) to 1.7% (10 nucleotides). Of the 15 variable sites, 12 were transitional substitutions, 2 were transversionalsubstitutions and 1 was transitional and transversional substitution. Phylogenetic analysis showed that all haplotypeswere highly interconnected with each other, in absence of phylogeographic structing. Each of 8 haplotypes was foundonly at one locality, and the other haplotypes were the widespread distributed in the different localities. The highergenetic diversity was found in the northern China populations than that in the southern China populations. The lowgenetic differentiation (FST=-0.06945-0.69857) and high migration rate (Nm=0.21575-infinite) of Chinese populations suggestthat dispersal over long distance is a major factor in the demography of S. avenae.