The rapid growth of the global population and the transformation and upgrading of dietary structures have led to a widening gap in the demand for cropland resources. Research on agricultural land reallocation that seeks to maximize cropland availability and increase grain production while also considering the preservation of natural ecosystems still has gaps. Following the theoretical assumptions of the agricultural land reallocation process, this study constructs a comprehensive framework for integrating scale, structure, and prioritization. Sichuan Province, China's main grain-producing region, is used as an example for a case study. The results demonstrate that the scale of agricultural land reallocation decreased from 56,742.01 to 44,965.52 km2 after correcting the evaluation of ecological conservation importance and crop production suitability under spatial and non-spatial constraints. There are significant differences in crop production suitability for agricultural land reallocation structures. Despite the wide spatial distribution of forest land, its utilization is challenging. Therefore, cropland, garden land, and grassland are prioritized for exploitation and utilization. In the eight priority zones for agricultural land reallocation, the main obstacles are constituted by single or composite factors of utilization convenience, spatial agglomeration, and facility stability. In general, agricultural land reallocation needs to be supported by considering different dimensions of resource availability, structural convertibility, and spatial compatibility. This approach maximizes the availability of resources for grain production while minimizing damage to natural ecosystems.