Abstract  [Aim]  Most beetles fly with their elytra open and their hind wings spread. However, most rose chafer and some dung beetle species fly by closing their elytra, elevating their side edges, and spreading their hind wings. From an aerodynamic perspective, flying with a closed elytra reduces air drag and is more efficient. Recent studies have established that the well-developed muscles and wings of the thorax are crucial for improving the flight ability of beetles, and the axillary joints of the hind wings play a key role in the flight of scarab beetles. However, research into the factors influencing this efficient flight mode and how the thoracic structure impacts flight modes remain limited. [Methods]  To explore the relationship between thoracic structure and flight mode, a comparative analysis was carried out on the morphology of the pronotum, mesonotum, metanotum, mesopleuron, metapleuron, elytra, mesosternum, and metasternum of nine beetle species from two families that utilize different flight modes. [Results]  In beetle species that fly with closed elytra, several distinct features were observed. The pronotum and elytra have lower arches, while the elytra are characterized by concaved edges and convex shoulders. The mesonotum is strongly sclerotized and the epimeron well-developed. The pleural wing process of the metapleuron is short, and the axillary segments of the base of the elytra tend to be integrated. In contrast, beetles that fly with open elytra, have strongly arched pronotum and elytra. The elytra are oval and the mesonotum is less sclerotized. The epimeron is undeveloped, the pleural wing process is longer, and the base axillary segments of the elytra are clearly structured. The thorax structure of beetles in related groups is similar. [Conclusion]  Beetles that fly with closed elytra have lower pronotum and elytra arches that may be have better aerodynamic effect compared to beetles that fly with open elytra. The significant sclerotization of the mesonotum, along with the protruding elytra shoulder, and developed epimeron all limit the expansion of the elytra from structural side. In summary, the two flight modes of beetles have distinct differences in the thoracic morphology and may influenced by both flight selection pressures and phylogenetic status.