Marginal land refers to areas with low agricultural productivity and economic returns due to soil limitations, severe constraints on water and thermal resources, and significant topographical challenges, making these areas ecologically fragile. Accurate identification and evaluation of the crop cultivation potential of marginal land are crucial for ensuring food security. Based on the concept of marginal land, this study classified and extracted eight types of land use: low-quality arable land, low-quality forest land, lowproductivity orchards, cultivable grassland, cultivable saline-alkali land, cultivable mudflats, cultivable sandy land, and cultivable bare land. Considering factors such as topography, soil, water resources, climate, and transportation accessibility, we assessed the suitability of marginal land in China for maize cultivation. The results showed that the total area of marginal land in China was 2.27 x 10(6) km(2), of which low-quality arable land accounted for 26.3%, while non-arable land (including cultivable grassland, low-quality forest land, low-productivity orchards, cultivable saline-alkali land, cultivable mudflats, cultivable sandy land, and cultivable bare land) accounted for 73.7%. The Northwest region contains the largest proportion of marginal land, representing 29.9% of the national total. Among the marginal land, areas highly suitable for maize cultivation account for 30.0%. If fully utilized for maize production, the potential yield increase could range from 35.3 to 46.3 x 10(7) tons, compared with the average corn yield of each province over the past five years. These findings provide a theoretical frameworks and scientific data to support the sustainable utilization of marginal land and the optimization of crop planting patterns in China.