The invention belongs to the technical field of agriculture, and particularly relates to application of 5-formyltetrahydrofolate in the aspect of increasing of the plant nitrogen utilization rate. Exogenous 5-F-THF promotes growth of a plant seedling under the low-nitrogen condition, and the nitrogen metabolism of the seedling is changed; the 5-leucovorin has important significance for understanding the biological functions of the 5-F-THF in a plant body and improving the plant nitrogen utilization efficiency during agricultural production.