A single bridge magnetic field sensor includes a fluxguide mounted to a surface of a substrate. A bridge unit includes first, second, third, and fourth magnetoresistive elements mounted around the fluxguide and mounted on the surface of the substrate. A switching circuit is electrically connected to two voltage inputs, two grounding terminals, two voltage output terminals, and the four magnetoresistive elements. The switching circuit can proceed with circuit switching according to a magnetic field in each axis direction to be measured, thereby changing electrical connection between the voltage inputs, the grounding terminals, the voltage output terminals, and the four magnetoresistive elements. A measuring unit is electrically connected to the two voltage output terminals and the four magnetoresistive elements. The magnetoresistances of the four magnetoresistive elements measured by the measuring unit and output voltages of the voltage output terminals can be used to obtain a magnetic field measurement result.