[Objective] Aiming at the difficulty of directly detecting the current in permanent magnet synchronous motor (PMSM) equipped with inductor-capacitor-transformer (LCT) high-order filter, this paper proposes a current cascaded observation method based on an extended state observer (ESO) and a Luenberger state observer (LSO). [Methods] The novel ESO cascaded method proposed in this paper required only the inverter-side current signal. The intermediate system state was obtained through the LSO, and disturbances were estimated and compensated in real-time by the ESO, achieving high-precision observation of the motor current. [Results] The experimental results showed that, under rated conditions, the motor current observation error was reduced by 3.2% with the novel ESO cascaded method proposed in this paper compared to the traditional LSO. [Conclusion] The proposed method achieves high-precision observation of high-order filtered PMSM current without requiring additional sensors or hardware modifications, effectively reducing system complexity and cost.