The invention discloses a method for producing a biocarbon-based slow-release nitrogen fertilizer, which is characterized by comprising the following steps: thermal cracking or gasifying corn straw, or apple tree waste branch, trunk and wood chip to obtain the biocarbon; mixing the biocarbon and an ammonium nitrate solution, or urea and the ammonium nitrate solution, fully stirring and drying, or adding a binder with 1-3% of total amount and sending to a granulation system for granulation, then drying to obtain the biocarbon-based slow-release nitrogen fertilizer product. The fertilizer has the advantages of simple and easy preparation technology, and low cost. The biocarbon-based slow-release nitrogen fertilizer contains 10-12% of nitrogen, the biocarbon carrier material is stable in soil, and is a good soil amendment and a carbon sequestration agent, soil is applied for improving soil fertilization, the nitrogen element of the nitrogenous fertilizer loaded by the biocarbon has slow-release effect, so that the loss of the nitrogen element can be reduced, the nitrogenous fertilizer utilization rate can be enhanced; the biocarbon can retain in soil for long-term to play the effects of carbon sequestration and carbon emission reduction, the biocarbon is helpful for alleviating climate warming, and biocarbon-based slow-release nitrogen fertilizer is a green fertilizer.