Abstract: The energy density of traditional lithium-ion batteries is approaching its theoretical limit, making it difficult to meet the growing demand for high-energy storage. All-solid-state lithium-selenium batteries (ASSLSeBs) with high-energy-density selenium cathodes have emerged as an ideal alternative due to their enhanced safety and absence of the shuttle effect. This article focuses on the selenium cathode in ASSLSeBs, highlighting core challenges and advanced modification strategies. It systematically analyzes the root causes of issues such as the poor electronic conductivity of Se and Li₂Se, as well as the high interfacial impedance resulting from inadequate solid-solid contact, thereby establishing a foundation for identifying viable improvement pathways. Subsequently, the article summarizes recent advances in enhancing the conductivity of composite cathodes and optimizing solid-solid interfacial contact. The fundamental principles, fabrication techniques, and performance enhancement outcomes of various strategies are critically evaluated. Finally, key challenges and future research directions for advanced cathode development in ASSLSeBs are discussed.