Abstract: To address the issue of roof support failure in roadways within the same rock layer, this study takes Xinglong Coal Mine as a case, conducting an in-depth analysis of the intrinsic relationship between rock strength and the RQD value (Rock Quality Designation). Using siltstone samples from the same rock layer, physical experiments were performed to measure the RQD values and corresponding compressive strengths of various samples. By meticulously comparing the rock failure characteristics of different borehole samples, the study reveals the evolution pattern of siltstone strength properties with RQD values under these specific geological conditions. The findings indicate a positive correlation between siltstone RQD values and rock strength (R²=0.962 6, p=0.036). The research results provide theoretical support and practical guidance for tunnel excavation, mining projects, and other types of engineering construction in this rock type, offering quantitative basis for optimizing tunnel support parameters in siltstone formations.