In view of the urgent need of miniaturization, high power density and high reliability for the electric servo system of aerospace equipment, adopting the servo system based on 5-phase permanent magnet synchronous motor (PMSM) is an effective solution. Under the condition of limited volume, the 5-phase fault-tolerant PMSM servo system driven by H-bridge has the ability of fault isolation and fault tolerance. In this paper, the fault-tolerant control algorithm based on decoupled space voltage vector is proposed to reduce the torque fluctuation in single-phase open fault condition. The proposed algorithm can reduce the output torque-ripple from 40% to 10% when the fault of one phase winding open occurs.