Forming an urban cold island network aligned with the concept of "Nature-based Solution" (NbS) by comprehensively coordinating natural landscape planning and the allocation of blue-green facilities is of great value for reducing the risk of extreme high temperature, reducing the risk of population thermal exposure, alleviating the vulnerability of urban climate under the background of increasing global warming. Taking Fuzhou City, one of China's "four new furnace cities", as the research object, and integrating multi-source geographic big data such as Landsat remote sensing images, land use data and open source Internet map data, utilizing circuit theory (CT), the modified floating catchment area(FCA) method, and a location-allocation (LA) model, a cold island network pattern in the high-density central city is constructed, which takes into account landscape ecology and environmental justice and integrates "point-axis-surface-network". The following conclusions are obtained: (1) The heat island effect in the central city of Fuzhou City is remarkable, particularly in the central and eastern areas with frequent construction activities and high population density; (2) The study identified 41 cold island core sources, 83 cold island corridors, 37 cold nodes, 67 hot nodes, 6 network clusters and 137 newly added blue-green spatial layout points. By organically combining the above structural elements of natural landscape, the blue-green spatial layout optimization was realized from the perspective of landscape connectivity and environmental equity; (3) An urban cold island network system characterized by "one ring, one axis, three corridors, and multiple points" has been established. "One ring" is a green ring around the city, which is composed of many natural mountains around the core area of the main city; the "one axis" refers to the main axis of ventilation corridor along Minjiang River; and the "three corridors" consist of "Shisun Mountain-Qishan Lake-Qishan Mountain", "Qingzhishan-Hongguang Lake-Aofeng Mountain", and "Minjiangkou-Nanshan Mountain-Damushan Mountain"; the "multiple points" include a large-scale cooling node composed of cold nodes and newly added blue-green space layout points in the central city. Furthermore, combined with the natural endowment advantages of river meet the sea and the integration of "mountain, water and city" in Fuzhou City, the improvement strategies to slow down the urban heat island effect are proposed. The results of this research can provide a transferable technical framework and practical cases for improving the local thermal environment of the city and planning and building a climate-adapted city under the principle that cities should be built by the people and for the people.