[Objectives]  The cotton bollworm, Helicoverpa armigera, caused significant damage to many crops in Ningxia and Inner Mongolia in 2017. To infer the origin of these pests in these two provinces, we studied the genetic structure of H. armigera in these provinces and in Northern and Northeastern China. [Methods]  We sequenced and analyzed the mitochondrial DNA COⅠ gene fragments (652 bp) of 162 cotton bollworms from 7 populations in China. [Results]  A total of 23 haplotypes were found, of which two source haplotypes (H16 and H23) were the most frequent. The haplotype diversity of all 7 populations was almost identical indicating that genetic differentiation between populations was low and non-significant. No significant correlation between genetic and geographic distances among populations was found. A neutrality test indicates that some populations may have experienced historical population expansion. [Conclusion]  High gene flow, which may be due to migration, probably occurs between cotton bollworm populations in Ningxia, Inner Mongolia and Northern and Northeastern China.