Multiphase permanent magnet synchronous motors, renowned for their high power density, low torque ripple, and exceptional fault tolerance, have emerged as a key research focus in aerospace propulsion systems. To address the single-phase open-circuit fault in dual three-phase permanent magnet synchronous motors (DT-PMSM) , this paper proposes a multi-objective optimization-based fault-tolerant field-oriented control strategy via multi-subspace coordination, aiming to enhance system reliability. First, a mathematical model of the motor under both normal operation and single-phase open-circuit fault conditions is established using the space vector decoupling method. Then, by coordinating current distribution between the d-q and \(z_1\) - \(z_2\) - \(z_3\) subspaces with the objectives of minimizing phase current amplitude and optimizing stator copper loss, high-precision control under fault conditions is achieved. Simulation results demonstrate that, compared to traditional current hysteresis fault-tolerant control, the proposed strategy reduces torque ripple by 75.26% and copper loss by 2.67% while maintaining output torque accuracy, significantly enhancing the system’s fault-tolerant performance and energy efficiency.