The experiment began in June 2011, and completed in December 2012 in the insects laboratory of the North-east Agricultural University, Harbin, China. The Hypena tristalis (Htri) was collected in the North-east Agricultural University Xiang Fang farm. For the purposes of research on the expression of heat shock protein 70 (HSP 70) gene of H. tristalis treated by heat stress, with changes in expression level in different induction times, RT-PCR technology was adopted for cloning to obtain a 1905 bp HSP 70 fragment of H. tristalis (GenBank accession number JQ316541), 635 amino acid residues were encoded, the predicted molecular weight was about 69.6 kD, and the isoelectric point was 5.36. The online bioinformatics prediction and analysis showed that the homology of the nucleotide sequence of H. tristalis HSP 70 with that of Helicoverpa armigera (accession number HM593518) was the highest one, which was 96%; the similarity was more than 70% while comparing with other insects. A 69.6 kD heterologous protein was detected in the HSP 70 prokaryotic expression (pET/Htri), and the protein was branded by Western blot detection. These results provide basic data for further research on the function of HSP 70 protein and for the pest control by thermal stress.