Based on the data of remote sensing images from Landsat in 1995 and 2015, this paper used the principal component analysis (PCA) method to determine the weights of four ecological indexes (greenness, dryness, wetness and heat), and then selected a evaluation model of remote sensing based ecological index (RSEI) to monitor and analyze the ecological environment quality of Weinan City from 1995 to 2015. The results showed that the mean values of RSEI in Weinan City increased from 0.489 to 0.556 during 1995-2015, which indicated the ecological environment qua-lity had been improved. The improved area of ecological quality was mainly distributed in the central area of Weinan City and its proportion was 49.6%. While the proportion of ecological environment degradation was 15.4%, and such areas were mainly distributed in some mine areas of Hancheng City and the southern Weinan (Weinan Section in North Qinling Mountains). The quality of ecolo-gical environment was greatly influenced by the urban planning and construction in the study area. Generally, the ecological condition of Weinan City had been improved, which benefited from the attention and investment of government.