This paper introduces a novel cooling electronic textile (CET) designed for outdoor health monitoring in hot environments. The CET aims to address the limitations of traditional wearable devices, which often suffer from reduced electrical performance, shortened lifespan, and skin burn risks when exposed to outdoor solar radiation. The CET integrates a spectrally selective passive cooling structure and a hierarchical sensing construction, achieving superior sensitivity (6.67 × 10^3 KPa^-1), stability, and excellent wearable properties such as flexibility, lightness, and thermal comfort. It can reduce the device temperature by up to 21 °C while maintaining reliable and accurate physiological signal tracking. The CET's core design involves passive radiative cooling, minimizing solar absorption and maximizing thermal radiation through the long-wave infrared atmospheric window (8–13 μm wavelength). The fabrication process involves carbonizing cotton fabrics, adding conductive electrodes, and incorporating nanostructured polyethylene. The CET's performance is characterized through current response, UV–vis–NIR reflectivity, IR emissivity, and thermal measurements, demonstrating its potential as a next-generation electronic textile for outdoor applications.This paper introduces a novel cooling electronic textile (CET) designed for outdoor health monitoring in hot environments. The CET aims to address the limitations of traditional wearable devices, which often suffer from reduced electrical performance, shortened lifespan, and skin burn risks when exposed to outdoor solar radiation. The CET integrates a spectrally selective passive cooling structure and a hierarchical sensing construction, achieving superior sensitivity (6.67 × 10^3 KPa^-1), stability, and excellent wearable properties such as flexibility, lightness, and thermal comfort. It can reduce the device temperature by up to 21 °C while maintaining reliable and accurate physiological signal tracking. The CET's core design involves passive radiative cooling, minimizing solar absorption and maximizing thermal radiation through the long-wave infrared atmospheric window (8–13 μm wavelength). The fabrication process involves carbonizing cotton fabrics, adding conductive electrodes, and incorporating nanostructured polyethylene. The CET's performance is characterized through current response, UV–vis–NIR reflectivity, IR emissivity, and thermal measurements, demonstrating its potential as a next-generation electronic textile for outdoor applications.