The identification and construction of ecological security pattern is an important way to ensure ecological security and sustainable development in semi-arid areas. Half arid areas on the loess plateau of the northwest inland at the county level administrative unit as the research object, combined with RS and GIS technology, the quantitative evaluation of ecosystem service function (biodiversity conservation, water conservation, soil conservation) and soil erosion sensitivity on the basis of the ecological source identification, and minimum cumulative resistance model is used to calculate surface resistance and build Lintao ecological security pattern. The results showed that the ecological source area of Lintao County was 243.79 km², accounting for 8.55% of the total area of the whole county. The ecological source area mainly distributed in the forest area of Nanping Mountain, Lanzhou Military Horse Farm in Maxian Mountain, the water conservation area of Taishi Town and the agricultural valley along Tao River. The ecological security buffer zone in Lintao County was divided into four categories:higher, high, medium and low level ecological security zones, which accounted for 12.71%, 47.81%, 32.51% and 6.97% of the total area respectively. Different measures should be taken to ensure regional ecological security in different ecological security zones. The identified 234 ecological corridors with a total length of 493.56 km, 185 radiation channels with a total length of 551.26 km, and 74 ecological strategic nodes constitute the ecological security pattern of Lintao County. The results of the study are expected to provide relevant references for the study on the construction of ecological security patterns at the county scale in semi-arid areas, and will also provide important guidance for the overall planning of land and space in Lintao County and the rational layout of urban land.