Abstract: In alignment with the vision of the United Nations Sustainable Development Goal 2 (SDG 2) to 'end hunger, improve nutrition, and promote sustainable agriculture,' this study refines the evaluation method for cultivated land carrying potential based on nutritional demands at different living standards and cultivated land productivity, thereby assessing the regional capacity for food security assurance. Firstly, this study applied the evaluation models of cultivated land production potential (including light-temperature production potential, climatic production potential, and the maximum yield of designated regional crops) and combined them with the nutrient output model. This approach transformed the output evaluation factor traditionally based on grain quantity into a more reasonable output of nutrients, thereby evaluating the cultivated land production potential of Shaanxi Province under different scenarios. Subsequently, combined with the varying demands for nutrients and dietary structures (plant-only diet and plant-animal diet) under different living standards (subsistence level, moderate prosperity level, and affluent level), the study calculated the cultivated land carrying capacity (potential) and cultivated land carrying capacity (potential) index of Shaanxi Province. Additionally, to clarify the improvement points of cultivated land production capacity in Shaanxi Province, the study further analyzed the pure grain output and comprehensive output of cultivated land in Shaanxi Province in 2023. Finally, based on the Bucket Theory, the study evaluated the population that the cultivated land in Shaanxi Province can support under different living standards. Key results show:(1) Under the scenario of maximum yield of designated regional crops, the cultivated land in Shaanxi Province can provide 1,374.608 trillion Kcal of energy, 39.82 trillion grams of protein, and 11.507 trillion grams of fat. These figures are 2.50 times, 2.88 times, and 1.55 times higher than the actual output level in 2023, respectively. The production potential of energy, protein, and fat shows characteristics of spatial agglomeration and hierarchical differentiation. (2) At the subsistence level, the maximum carrying capacity of cultivated land in Shaanxi Province reaches 672.36 million people; under the scenario of maximum yield of designated regional crops, this value is 218.19 million people. When nutrient constraints are considered, fat acts as the limiting factor for Shaanxi’s maximum cultivated land carrying potential. Under the mixed plant-animal dietary structure, both the carrying capacity derived from cultivated land output and the limiting nutrient factors in Shaanxi exhibit significant changes—specifically, the nutrient restricting the maximum carrying potential shifts from fat to energy. At the affluent level, with nutrient constraints incorporated, the most attainable cultivated land carrying potential of Shaanxi Province is 50.1209 million people, as calculated under Output Scenario III. (3) High carrying potential occurs mainly in Northern and Central Shaanxi, with no overload observed across any living standard or dietary structure. Following changes in nutrient constraints, some counties and districts in Yulin have exhibited an increase in carrying potential. This trend is closely associated with the capacity of food to supply nutrients. (4) Cultivated Land Carrying Capacity Index exhibits significant spatial heterogeneity with a Z-shaped distribution: High values cluster in Guanzhong, Southwestern Shaanxi, and Central Northern Shaanxi; Low values concentrate in Western Shaanxi and Northern Yulin. This study quantifies the theoretical threshold of the carrying potential of cultivated land resources in Shaanxi Province with the improvement of living standards and nutritional needs. The research provides evidence for Shaanxi Province’s ability to support food security guarantees during the stage of residents' affluent life.