【Objective】To address the unclear weathering characteristics of gravel of northwestern gravel-mulched farmlands under water-rock interaction and its subsequent effect on topsoil nutrient supplementation. 【Method】A semi-field experiment was conducted using degraded gravel-mulched farmland that had been fallowed after over 30 years of continuous cropping. Gravels within the predominant particle size range were selected to analyze their physical and chemical weathering responses to dry-wet cycles. Furthermore, the regulatory mechanism of element leaching on topsoil nutrients was elucidated. 【Result】The results indicated that: (1)the gravel was primarily composed of silicate minerals. Under dry-wet cycling, weakly alkaline water caused limited chemical weathering, making physical weathering the dominant process. Water-rock interaction significantly promoted gravel mass loss and increased water absorption efficiency (P < 0.05). Fine-grained gravel (5-10 mm) was the most responsive, exhibiting peak mass loss and water absorption rates of 2.09% and 1.70%, representing increases of 242.11% and 23.10% compared to the control group without dry-wet cycles. (2)Although no significant transformation was detected among secondary minerals, chlorite experienced the most substantial loss (10%) in fine-grained gravel due to temperature fluctuations and leaching. The dissolution of magnesium-rich chlorite, which primarily exists as pore fillings, led to varying enrichment of elements in the topsoil, showing a release sequence of Mg > Ca > Fe > Mn > K > Zn. (3)Correlation and principal component analyses confirmed that the physical weathering characteristics of the gravel were significantly correlated with the content of lithophilic elements in the soil (P < 0.05). 【Conclusion】In conclusion, dry-wet cycling promotes the weathering process of mulch gravel, and element leaching during breakdown plays a crucial role in regulating topsoil nutrients. This study provides new insights for improving the soil environment, mitigating degradation, and facilitating reclamation in gravel-mulched farmlands.