A fault-tolerance control strategy based on the constant magnetomotive force (MMF) is proposed for a five-phase permanent-magnet linear synchronous machine (FP-PMLSM) under one-phase fault condition in this article, which aims to keep steady operation during a short time. First, the mathematical model of FP-PMLSM having one-phase open-circuit fault is analyzed. Based on the analysis, the fault-tolerance strategy is derived under the constraint of constant copper loss. This strategy makes the fault-tolerance currents become unbalanced seriously and the maximum thrust force reduced. Then, the proposed method is introduced and the corresponding fault-tolerance currents are calculated. The fault-tolerance currents of both strategies are optimized in order to reduce the second harmonic component of the thrust force ripple. Finally, the investigation of the electromagnetic performance is carried out in detail. By comparison with the constant copper loss strategy, the proposed strategy is proved to output a steadier thrust force.