Based on the principle of the absorption of magnetic fluid by magnetic field, the design principle of ferric nitride magnetic fluid sealing device and its working process were discussed. The pressure bearing capacity of the designed static magnetic fluid seal was theoretically analyzed and experimentally verified by conducting a series of sealing tests. Accordingly, a safety valve was successfully constructed by making use of the ferric nitride magnetic fluid sealing. A pilot safety valve device was found to pass a series of tests including the opening pressure stability test, controllability test of the opening pressure, and sealing performance test. It was also found to operate smoothly for a duration above 10000 h.