In this chapter, the combustion characteristics and fracture toughness of epoxy glass fiber/phenolic composites under different thermal and oxidation conditions were investigation. With applications in high-performance industries such as aerospace and automotive, these composites are tested for their ability to resist fracture and mitigate the spread of cracks during combustion. The study examines key parameters such as the limiting oxygen index (LOI), heat release rate (HRR), and the material’s response to varying intensities of thermal radiation. Experimental results demonstrate that the fracture toughness of the composites improves with increasing fiber content, while the combustion process is significantly influenced by thermal conditions. By understanding the combustion behavior and optimizing the material’s resilience to fire and mechanical failure, this work provides insights into improving the safety and performance of epoxy glass fiber/phenolic composites for fire-sensitive applications. The findings contribute to the growing need for more sustainable and fire-resistant composite materials in high-temperature environments.