Optical current transformers align with the intelligent and digital development needs of new power systems. However, the existing optical current transformers lack temperature-resistant solutions for wide temperature range measurements in power systems that simultaneously meet real-time processing requirements and ensure long-term operational stability. To address these issues, a dual-strip temperature-immune magneto-optical current transformer (DS-MOCT) based on the Koopman adaptive filtering is proposed. First, the principles of magneto-optical sensing and the temperature perturbation mechanism in magneto-optical sensing are introduced. By using the Jones matrix, a polarization analytical model for optical current sensing at arbitrary angles of the polarizer-analyzer in a straight-through optical path configuration is formulated. Subsequently, the influence of varying polarizer-analyzer angles on the transformer′s output is analyzed. A temperature compensation method for specific angles of the polarizer-analyzer is proposed. This enabled the construction of a temperature-resistant DS-MOCT structure comprising a measurement arm and a temperature compensation arm. The measurement arm outputs the measured current information, while the temperature compensation arm generates temperature compensation signals. These compensation signals are applied in real-time to counteract temperature disturbances in the measured current signal. Consequently, the DS-MOCT produces temperature-immune measurement current values resilient to thermal perturbations. The error sources of DS-MOCT are analyzed, and a Koopman theory-based denoising method is proposed. Subsequently, finite element simulations are performed to model the DS-MOCT′s multi-physics coupling environment. Results demonstrate the optical wave′s thermal stability by visualizing its temperature resistance behavior. Finally, the DS-MOCT experimental system with hardware-software co-design is constructed. The experimental results show that, within a broad temperature range of -40℃ to 40℃, the DS-MOCT exhibits a measurement error of less than 0.2%, complying with the Class 0.2 measurement standard for electronic transformers specified in GB/T 20840.8—2007. The dynamic response time remains under 14 ms, satisfying the real-time monitoring requirements of power systems. The proposed Koopman adaptive filtering-based DS-MOCT resolves the trilemma of temperature resistance, real-time performance, and long-term operational stability in optical current transformers within new power systems.