To enhance the photothermal response of hexanitrostilbene （HNS） under laser initiation， a core-shell composite（HNS@PDI） was prepared by a combining strategy of molecular structure regulation and self-assembly surface deposition method， and the influence of the molecular structure of PDI on its photothermal conversion efficiency and the laser ignition performance of HNS@PDI were systematically studied. The perylene imide （PDI-C12） modified with a dodecyl chain can easily assemble into a J-stacking structure that is conducive to non-radiative exciton transitions. Under 1064 nm laser irradiation， the composite modified with PDI-C12 exhibits a photothermal conversion efficiency of 69.3%， which is 110% higher than that of the short-chain analog PDI-C2（32.9%）. When the PDI loading was optimized to 5%， the laser ignition delay time was reduced to 22 ms at a laser power of 10 W and energy density of 80 W·cm^-2. The PDI shell also significantly improves the safety performance of this composite. The critical impact energy of the composite increases from 5 J to 30 J， and the critical friction force is above 360 N. In addition， the PDI layer effectively inhibits photodecomposition. This study effectively improved the laser ignition performance of HNS， while enhanced the safety and photostability， providing new ideas for the development of high-performance laser ignition agents and photosensitizers.