Abstract: The structural materials employed in special power reactors are subjected to exceptionally harsh service environments, enduring the combined effects of high temperatures, intense irradiation, and high stresses. Molybdenum-rhenium (Mo-Re) alloys, renowned for their high melting points and superior mechanical properties at elevated temperatures, are considered promising candidate materials for such reactors. The addition of Re significantly enhances the mechanical properties of Mo-based alloys. However, it also leads to irradiation embrittlement under irradiation conditions. The irradiation embrittlement behavior of Mo-Re alloys is closely tied to the generation and evolution of irradiation-induced defects. Currently, the influence of the Re element on the generation and growth behavior of irradiation defects in Mo-based alloys remains inadequately understood. In this study, molecular dynamics simulations were utilized to investigate cascade collisions in Mo-Re alloys, with a particular emphasis on elucidating the mechanisms by which varying Re contents and primary knocked-on atom (PKA) energies affect the initial generation and subsequent evolution of defects. The analysis focused on the number of Frenkel defect pairs generated during cascade collisions in both pure Mo and Mo-Re alloys under different PKA energies, as well as information on defect clusters and dislocation loop structures. The study explored the influence of Re content on the cascade collision behavior of Mo-based alloys. Compared to pure Mo, Mo-7.7Re and Mo-27.2Re alloys exhibit an increasing trend in the number of Frenkel defect pairs during the thermal spike phase of the cascade collision, while approaching similar levels at steady state. This phenomenon is primarily attributed to the introduction of Re atoms, which prolongs the thermal spike duration and reduces energy dissipation capacity, thereby facilitating the recombination of more defects. After the cascade collision, Mo-Re alloys predominantly feature interstitial atom clusters. As the PKA energy increased, both the number and size of these defect clusters show an upward trend. Dislocation loops of the 1/2<111> interstitial type were observed in both pure Mo and Mo-Re alloys, and their sizes increased with higher Re content. This may stem from the fact that introducing a high concentration of Re atoms elevates the temperature in the cascade core region of Mo-based alloys, promoting the migration of interstitial atoms and vacancies, and consequently leading to the formation of larger dislocation loops. In conclusion, the findings of this study provide a theoretical foundation for understanding the irradiation damage mechanisms in Mo-Re alloys. By elucidating the effects of Re content and PKA energy on the generation and evolution of defects during cascade collisions, this research contributes valuable insights into the development of more radiation-resistant materials for special power reactors. Further investigation into the long-term irradiation behavior and microstructural evolution of Mo-Re alloys will be essential for optimizing their performance in such demanding applications.