To address reflective cracking and arching issues in road surfaces in Xinjiang, an investigation was conducted on the gradation design methodology and road performance characteristics of an oversized cement-treated gravel base (LCGB-50). Using the stepwise filling method and the variable-i approach, the optimal coarse-to-fine aggregate ratio was selected based on 7 day mechanical strength, and a reasonable gradation range was determined for skeleton-dense cement-stabilised gravel with oversized particles. The VCADRF method was applied for computational validation of the gradation design. The mechanical performance and frost resistance of LCGB-50 were verified through long-term strength tests and freeze-thaw cycle experiments. Finally, the serviceability of the material was evaluated using data collected from field trial sections and long-term environmental monitoring points. The results indicate that when the i value was set to 0.70 with a coarse-to-fine aggregate ratio of 60:40, the 7 day unconfined compressive strength and splitting tensile strength reached optimal values of 9.78?MPa and 0.91?MPa, respectively. The VCADRF test results showed an error margin within 5%, confirming that a strongly interlocked, skeleton-dense structure had been formed in the cement-stabilised gravel. Cores extracted from test sections remained intact, with 7 day compressive strengths exceeding 8?MPa, thereby meeting the design strength requirements and demonstrating high strength and uniform compaction. Monitoring data revealed that within a temperature range of –20?℃ to 40?℃, LCGB-50 exhibited superior strain recovery capability, which was 14% higher than that of conventional gradation sections. The occurrence of reflective cracking was reduced by approximately 57%. These findings demonstrate that the coarse-graded cement-stabilised gravel base possesses enhanced adaptability to temperature and stress variations, with reduced deformation fluctuation, indicating a clear performance advantage in mitigating the development of reflective cracking.