[Objective] The aim was to explore the relationship between the Dorsal and diapause development of Delia antiqua. [Method] The full-length cDNA of Dorsal in D. antiqua was cloned through RACE. The similarity among deduced amino acid sequence of Dorsal cDNA and the Dorsals of other 14 insect species were compared, and the phylogenetic analysis of these Dorsals was conducted. The expression level of Dorsal gene in winter-, summer-and non-diapausing pupae was analyzed. [Result] The full-length of Dorsal cDNA sequence, 2 412 bp, was obtained with ORF 1974 bp, which coded 657 amino acids with predicted Mw 72.9 kDa and PI 8.5. The result of similarity comparison indicated that the DaDorsal was most related to those of Drosophlia melanogaster and Drosophlia pseudoobscura. The result of semi-quantitative RT-PCR analysis showed the expression level of Dorsal gene increased in characteristic duration of winter-, summer-and non-diapausing pupae, especially at the late diapause, which might imply its relationship to D. antiqua diapause and development. [Conclusion] The study lays the foundation for further study on gene function of Dorsal in insect diapause and development.