Ecological security is an important guarantee for maintaining economic, social and ecological sustainable development. Since the implementation of the Western Development and the "One Belt, One Road" strategies, the western cities and towns have developed rapidly and the economic benefits have been greatly improved. However, the ecological environment is facing great challenges. Therefore, this paper takes Gansu Province, an important ecological barrier area in the northwestern region, as the research object. By improving the traditional ecological footprint model based on the concept of "provincial hectare", we evaluated the ecological environment evolution characteristics and ecological security status from 2005 to 2015 and quantitatively analyzed its driving factors. The results showed that (1) the per capita ecological footprint and per capita ecological carrying capacity of Gansu Province increased from 0.51 hm²/person and 0.22 hm²/person to 0.69 hm²/person and 0.47 hm²/person from 2005 to 2015, respectively. The ecological carrying capacity increased at a faster rate, but the natural resources were still in a state of "supply less than demand". (2) The per capita ecological deficit in Gansu Province changed from -0.20 hm²/person to -0.33 hm²/person, and the degree of ecological deterioration increased continuously. The ecological pressure also rose from 2.07 to 2.74, and the ecological security was in a very unsafe state. The overall pattern of "northwest high and southeast low" was consistent with the urbanization layout. (3) There were significant differences in the decision-making power of various influencing factors on ecological security change. Among them, per capita GDP had the strongest disturbance to ecological security. The other factors affected the degree of per capita energy consumption > the proportion of secondary industry to GDP > urbanization rate > population Density > Science and education expenditure as a percentage of total expenditure.