A five-phase six-leg switching power amplifier with a fault-tolerant leg is proposed for a five-degree-of-freedom magnetic bearing system. Compared with the traditional five-phase six-leg switching power amplifier, it adds a fault-tolerant leg to achieve fault-tolerant operation. Taking the neutral leg as an example, the simulation analysis is carried out by MATLAB software. The simulation results verify the rationality and correctness of the design of the five-phase six-leg switching power amplifier with fault-tolerant leg.