Since the 21st century, the cultivated area, irrigated area, and main grain-producing zone have been continuously concentrated to the North of China, and the North-to-South grains transportation has further aggravated the dislocation of land resources and water resources, which leads to the increase of agricultural water resources stress, and the unsustainability of underground water in the main grain-producing zone to the north of the Yellow River. To ensure national food security and provide rational basic guarantees for agricultural water resources, based on the analysis of the agricultural water resources situation, the grain production and consumption, the spatial distribution characteristics of food crop irrigation water requirements, and the precipitation adapting cropping areas in China, the paper employed the irrigation quote method to calculate the minimum thresholds of farmland irrigation water requirements in 2025 and 2030 under the condition of the irrigation method adjusted and rational irrigation scale constrained by the grain consumption demand and the total water use control red line in future. The results show that, to meet the water demand for high-standard farmlands of 66.67×10⁶ hectares in the future, a bottom line of 3.23×10¹¹ m³ water for farmland irrigation should be guaranteed while strengthening water-saving conditions, and approximately 6.44×10⁹ m³ unconventional water should be exploited to supplement fresh water shortage. Strategic measures of establishing water-saving and high-efficiency modern irrigation farming and water-collecting and efficiency-improved dry farming systems are proposed. To this end, the following measures should be stressed: precipitation adapting cropping should be promoted to improve rainwater utilization efficiency, engineering and agronomic measures should be taken to increase the utilization efficiency of irrigation water, utilization of unconventional water resources should be increased, and water resource management should be enhanced.