The invention discloses an even-number closed loop optical fiber magnetometer for achieving working point control and magnetism return-to-zero, which comprises a light source drive circuit, a light path sensing unit, a photoelectric conversion unit, an A/D conversion unit, a digital signal processing unit, a D/A conversion unit and the like, wherein the light path sensing unit comprises a DFB laser, a three-port optical circulator, an integrated optical phase modulator and the like, and has simple structure; the digital signal processing unit various control time sequences, low-frequency modulation square wave and a synchronous clock of a high-frequency sine modulation signal, completes relative demodulation of low-frequency phase drift and generates compensation phase shift digital quantity, secondarily demodulates a signal subjected to relative demodulation of the low-frequency phase drift to generate the magnetic field signal feedback quantity, forms the even-number closed loop detection, achieves the stable control and magnetism return-to-zero feedback of an interferometer orthogonal working point, improves the anti-jamming capability and the stability of the system, expands the dynamic range of measuring, and improves the sensitivity for measuring the magnetism.