The invention discloses a single-phase magnetically constrained fault current limiter. The limiter comprises an iron core, wherein two windings in serial connection are wound on the iron core, magnetic fluxes generated by the two windings in the iron core are offset to zero, and two ends of one winding are connected with a bypass switch in parallel. In normal working condition, when the bypass switch is turned on and off, magnetic fluxes generated by the two windings in the iron core are offset to zero, and the single-phase magnetically constrained fault current limiter has no impact on the transmission power and the line current; when short circuit occurs, the bypass switch is turned off rapidly so as to recover offset magnetic fluxes in the iron core to rated magnetic fluxes, so that rated impedance is generated and the fault current level is limited.