The Kuroshio Extension (KE) in the Northwest Pacific Ocean is one of the most dynamically-complex regions in the global ocean, but is one of the regions with the least long-term continuous observations. Since 2014, Ocean University of China has started the construction of Kuroshio Extension observation system and carried out a series of far-reaching scientific-research-oriented in-situ observational experiments. In 2020, the phase I of the Kuroshio Extension Mooring System (KEMS) has been successfully constructed, providing real-time hydrological and meteorological data. In the next phase (2021-2025), this system will focus more on ocean multidisciplinary observations, to study the ocean carbon cycle, multi-scale coupling of physical/biological processes, ocean energy cascade and climate effect.