Aiming at the features of Haihe River basin, and by using RS and GIS technologies in combining with qualitative and quantitative analyses, a regionalization was conducted on the ecological function of the basin. The Haihe River basin could be divided into 5 ecoregions, 24 sub-ecoregions, and 114 eco-functional zones. Furthermore, 11 critical eco-functional zones were identified, according to the dominant functions (water conservation, soil conservation, wind prevention and sand fixation, and biodiversity protection) at basin scale. This regionalization made clear the regions important for the ecological security of Haihe River basin, which could guide the orderly exploitation and utilization of natural resources and the rational distribution of industries, offer scientific basis for the ecological environment protection, and maintain the ecological security of the basin.