The common biological stress in Brassica napus production seriously restricts the development of China’s Brassica napus industry. Therefore, improving the insect resistance of Brassica napus is of great significance for the development of China’s Brassica napus industry. At present, no monogenic resistance against any insect pest has been reported in oilseed rape, and no cultivars could show resistance against any of the commercially important insect pests [29]. Additionally, the primary germplasm pool of Brassica napus is thought to lack resistances to many insect pests [5]. Therefore, the research on insect resistance genes in Brassica napus remains to be explored at home and abroad.Brassica plants contain many groups of secondary metabolites which are sometimes lineage specific. Secondary metabolites are often associated with regulation of growth, development and plant defense [30]. Major secondary metabolites associated with insects in the Brassicaceae include terpenoids, phytosterols, flavonoids, phenolics, cyanogenic compounds and alkaloids [31]. However, most of the studies were about the effects of glucosinolates [32,33]. The effects of other secondary metabolites in the Brassicaceae are scarce [34], which makes modifying secondary metabolites for insect resistance a breeding target with a medium- to long-term perspective [5].Recent studies have shown that, when the Arabidopsis PEN1 gene (AT4G15340) was overexpressed, the plants showed strong resistance to Plutella xylostella infection [28]. Pentacyclic triterpene synthase 1 (PEN1) has been reported to be a key enzyme in the biosynthesis of the volatile homoterpene (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) [35]. Additionally, DMNT repels Plutella xylostella, eventually killing larvae by disrupting their peritrophic matrix (PM) [28]. In general, sequences with high similarity retained during long-term evolution are conserved and usually have similar functions. In this study, 12 PEN1 homologous genes in Brassica napus were identified by bioinformatics methods and analyzed systematically from the aspects of phylogenetic evolution, gene structure, protein physicochemical properties, cis-acting elements and gene tissue expression characteristics. Through the analysis of cis-acting elements in the promoter region, we found that all the PEN1 homologous genes contained light responsiveness elements. Most of the genes contained a gibberellin-responsive element, meJA-responsive element and abscisic-acid-responsive element. Since plant hormones play an integral role in plant defense responses [36], among them, jasmonate (JA) and salicylic acid (SA) pathways induce defense systems against herbivores in cruciferous plants [37,38]. Therefore, we hypothesized that the PEN1 homologous genes might regulate the resistance response of Brassica napus to pests through different hormone response pathways. In addition, among all the PEN1 homologous genes, only BnaA04g10140D and BnaC03g05360D contained the defense and stress responsiveness element, which suggests that these two genes may play important roles in the defense and stress response pathways of Brassica napus. According to the results of fluorescence quantitative PCR, we found that the expression level of 9 PEN1 homologous genes in Chuangza 8 was significantly higher than that in Heyou 202, including these two genes. Based on the above analysis, we can focus on further functional verification of BnaA04g10140D and BnaC03g05360D in the future.In recent years, transgenesis has been broadly applied to protect some major crop species against coleopteran and lepidopteran insect pests. Since the mid-1990s, genes for endotoxins have been used commercially in transgenic crops, such as maize and cotton, but not in oilseed rape [39]. The aim of this study was to provide a theoretical basis for screening insect resistance genes from the Brassica napus genome and analyzing the molecular mechanism of insect resistance in Brassica napus. Subsequent studies will focus on this direction to verify the function of genes and their participation in the molecular mechanism of insect resistance, in order to lay a foundation for the study of insect resistance in Brassica napus.