The invention discloses a method for determining a dry crop nitrogen input environment threshold based on a regional scale. The method comprises the following steps: determining a nitrogen application rate under a highest relative yield within a region, primarily determining the dry crop nitrogen input environment threshold based on the regional scale, evaluating a regional yield risk and an environmental risk of the primarily determined nitrogen input environment threshold, and finally determining the dry crop nitrogen input environment threshold based on the regional scale. The method disclosed by the invention is used for determining the nitrogen application rate corresponding to the highest relative yield with the nitrogen input environment threshold based on the regional scale of 98%. The nitrogen input environment threshold determined by the method disclosed by the invention is obtained based on the historical data of the regional scale and current experimental data of a regional scale soil type, the method has wide regional adaptability and feasibility, the yield risk and the environmental risk are evaluated by test points, and the dry crop nitrogen input environment threshold is finally determined, so that the implementation effect is safe and reliable. A high crop yield can be maintained, and the environmental pollution risk caused by excessive nitrogen fertilizer application can be effectively and greatly reduced.