The invention relates to a preparation method of trace nitrogen-containing RE-Fe-B system permanent magnetic material. The method comprises the following steps: (1) mixing raw materials according to designed formula requirements, (2) quickly hardening flakes, (3) performing hydrogen decrepitation, (4) crushing in low-temperature nitrogen protection or argon protection, (5) jet milling in low-temperature nitrogen protection or argon protection, (6) mixing, (7) shaping, (8) sintering, (9) aging and (10) processing and detection; all material conversion processes are controlled by full sealing. The RE-Fe-B system rare earth permanent magnet prepared by the method only contains trace nitrogen, and anticorrosion property of the magnet is greatly enhanced.