【Background】The western flower thrips, Frankliniella occidentalis (Pergande), spreads rapidly since it invaded China in 2003, and has caused severe damage in some areas. It poses a great threat on the normal development of vegetables, flowers and fruits.【Method】In the present study, a mitochondrial DNA (mtDNA) marker analysis based on 175 COⅠ gene sequences was used to examine the genetic variability and population structure of F.occidentalis of 13 populations collected in different geographic areas of China.【Result】 Thirteen haplotypes were identified. The haplotype diversity (Hd=0.691) of different geographic populations of the thrips was much higher than the nucleotide diversity (π=0.0065). The total genetic fixations index (Fst) was 0.24 and gene flow (Nm) 0.78, respectively. Evaluation of Fst and Nm between geographical populations indicated that genetic differentiation may have occurred. The analysis of molecular variance (AMOVA) between geographical populations of F.occidentalis showed that the genetic variation mainly occurred within the same populations. The cluster analysis based on haplotypes of COⅠ gene sequences from domestic and foreign populations indicated that two strains of F.occidentalis, the glasshouse strain and the lupin strain, were detected in China. The lupin strain could be from New Zealand and Holland; however, the glasshouse strain should have multiple sources of invasion. 【Conclusion and significance】In China, the western flower thrips was first recorded on pepper plants in a glasshouse in Beijing, two years later it was reported in Yunnan. Since then, F.occidentalis has rapidly expanded, which not only correlated with the activities of international trade, but also with the domestic transportation of vegetables, flowers and fruits as well as tourism. The present results should be useful in reduce further invasion of F.occidentalis and monitoring its spread through China.