Abstract: In the arid area of northwest China, the ecological security of land has a direct impact on oasis cities whether it has the foundation to develop sustainably in the future. Choosing the second largest city in Xinjiang, Korla City as the study area, using quantitative analysis method, and based on the economic feasibility index, non-environmental resources reasonable coefficient and non-social acceptance index, this paper built a triangle model which was further divided into five regions A-E representing the different states of land ecological security. A point in the triangle model was determined based on the values of the three complex indices, which represents the state of land ecological security of the area. And then an evaluation index system was constructed to analyze and evaluate the land ecological security state evolution and the main affecting factors in Korla City from 2009 to 2014. The degree of influence of each index is calculated by normalizing the raw data with range method first, then calculating the weight of every index with entropy weight, and getting three composite index finally. The results show that during the study period, the land ecological security state in Korla City was very unsafe, since 2011, the state gradually changed to unsafe development, and this trend was stable. Therein, the economic feasibility of the index increased by 1 350%, non-social acceptability reduced by 18%, and non-resource environment rationality increased by 21%, indicating that the development of economy and society in Korla was good, but the land ecological environment worsened. According to the analysis of influencing factors, the ecology are fragile in common in oasis cities in areas, which is an inevitable issue during development. Korla City, driven by resource and industry, was developing inevitably in the mode of "pollution first, treatment later", but the rapid development of economy has led to an expansion of the built-up area, more introduction of new technologies and management model in the urban basic services, and a large number of foreign population, making the land urbanization and population urbanization gain a greater development space. Now, Korla City should improve the standard rate of industrial emissions, reasonably arrange the layout of the industrial parks and urban living areas, and further strengthen the treatment of urban life pollution to avoid the effect of peri urban agriculture, so as to ensure steady economic growth, and to provide a basis for management and ecological restoration.

Key words: land ecological security, northwest arid area, oasis, Korla City