Abstract In this study, the actin A3 promoter was inserted into piggyBac and constructed into pBacA3, which was inserted into piggyBac. The promoter was composed of the promoter and nerve-specific 3xP3 promoter, the enhanced green fluorescent protein (EGFP) gene and the SV40 polyadenylation recognition sequence. EGFP and pBac3xP3 EGFP transposon were injected into the early fertilized eggs of Spodoptera litura to detect whether they were expressed. The results showed that both vectors could be expressed in moth eggs, and positive individuals were obtained. The results showed that the expression rate of pBacA3 EGFP was higher than that of pBac3xP3 EGFP, and the proportion of EGFP in hatching larvae was higher than that in the latter. The results showed that pBacA3 EGFP was more suitable for Spodoptera litura Transposable carrier. In vitro transient expression of the transgenic vector of Spodoptera litura was not only the first step necessary to successfully carry out the transgenic gene of Spodoptera litura, but also itself can be applied to the study of gene function, which laid the foundation for the genome research of Spodoptera litura.