The invention discloses a spherical three-axis fluxgate sensor, which comprises a spherical three-axis fluxgate probe, an excitation circuit and a signal processing circuit, wherein the spherical three-axis fluxgate probe comprises an excitation winding, a three-axis detection winding and a three-axis feedback winding, and the excitation circuit is used for providing voltage excitation for the excitation winding; the three-axis signal processing circuit is used for receiving induction pulse signals of the three-axis detection winding, providing feedback current for the feedback winding and outputting analog voltage signals; and the excitation circuit comprises a linear stabilized voltage source, an oscillator, a frequency divider, a monostable trigger, a P-NMOS transistor H bridge and a high-velocity electron isolator, and the signal processing circuit comprises an instrument amplifier, a phase-sensitive demodulator, an integrator and a servo trans-conductance amplifier. The spherical three-axis fluxgate sensor can adjust the pulse width so as to regulate the length of time when a non-magnetic spherical core stays at a magnetic conduction state and a magnetic saturation state, further realizes mutual independence of feedback current and final output current and reduces a measurement error caused by sharing.