As an importantly strategic water resource reserve area in China, Fuxian Lake basin plays an important role in ecological security. This study takes the watershed as the research object, adopts the State-Hidden-Response(SDR) model, exploratory spatial analysis method, and analyzes the spatial differentiation characteristics of ecological security from 1987 to 2020 based on grid scale. The results indicate that:(1) Spatial difference of ecological security in Fuxian Lake basin is obvious. The ecological security status is mainly moderate security (Grade IV) and high security (Grade V), which are mainly distributed around the basin. Ecological insecurity (Grade I), relatively insecurity (Grade II), and critical security (Grade III) are concentrated in the densely populated agricultural areas on the north and south banks of the basin and the middle of the east bank. (2) The spatial agglomeration effect of ecological security in the study area is obvious overall spatial autocorrelation coefficient is high and rises gradually. The agglomeration effect is enhanced, which is mainly high (HH) and low (LL). The HH area is concentrated in the northwest, southeast, and central areas of the west bank of the basin. The LL area is distributed in the densely populated areas on the north bank of the basin and the agricultural areas on the south bank. (3) The spatial differentiation of ecological security in the study area is obvious in different land use types, slopes and population densities. Ecological insecurity (Grade I) is mainly distributed in construction land, ecological insecurity (Grade II) and ecological critical security (Grade III) are mainly distributed in cultivated land, and ecological medium security (IV) and high security (V) are mainly distributed in forest land. Ecological security has obvious differentiation characteristics with slope and population density respectively. With the increase of slope, the level of ecological security is high, the population density is larger, and the quality of ecological security is lower.