[Objectives]  In recent years, the Western flower thrip, Frankliniella occidentalis (Pergande), has been found in several Chinese provinces and the range of this pest appears to be expanding in China. Heat shock protein 70 (HSP70) is one of the most important members of the heat shock protein family and plays a very important role in thermotolerance in insects. The aim of this study was to clarify differences in the expression of HSP70 in adult male and female F. occidentalis that were subject to temperature stress, both to further explore the molecular mechanism by which this species responds to temperature stress, and to provide a theoretical basis for the control of this pest. [Methods]  The Western flower thrip HSP70 gene was cloned using RT-PCR and RACE. The genomic sequence was then determined by genomic validation, and the position and size of the intron were analyzed by cDNA sequence analysis. Finally, Real-time PCR was used to analyze the expression patterns of HSP70. [Results]  The HSP70 gene obtained was named Fohsp703 (GenBank accession number: KY914546) which had a complete cDNA sequence of 2 106 bp in length, an open reading frame (ORF) of 2 040 bp and encoded 679 amino acids with a predicted molecular weight of 73.6 ku. Its amino acid sequence contains three HSP70 family signature sequences, indicating that HSP70 is a member of the heat shock protein family. However, unlike the HSP70 genes of other species, the Fohsp703 protein sequence ends with APAA, and phylogenetic analysis also suggests that Fohsp703 differs from the HSP70 genes of other insects. Analysis of its genomic structure revealed that Fohsp703 does not contain introns. The expression of Fohsp703 was significantly elevated by heat and cold stress. Expression was higher in adult females than in males, peaking at 37℃ and ﹣12℃, respectively. [Conclusion]  The Western flower thrip HSP703 gene is a novel member of the insect HSP70 family and plays an important role in resistance to extreme temperatures.