A fatty-acid binding protein (FABP) gene of Helicoverpa assulta was cloned and expressed for further study on its function. The cDNA encoding the FABP was isolated from the fat body and blood cell of H. assulta larvae by reverse transcription polymerase chain reaction (RT-PCR). The fragment containing FABP gene was inserted into pGEX-4T-2 expressive vector, and the expression was induced by IPTG and then checked. The results showed that FABP in H. assulta was 399 bp in length (registered in GenBank with the accession no. DQ299942), encoding a peptide of 132 amino acid residues, and the predicted molecular weight was 15.0 kD. The FABP was fused with GST. Checked with SDS-PAGE, the prokaryotic expression product molecular weight was about 41 kD, and it was further confirmed with Western blot.