Abstract: 【Objective】 The Gansu section of the Weihe River Basin occupies a very important strategic position in the improvement and development of the Yellow River,and measuring its ecological security index and grade can provide a theoretical basis for the construction of ecological civilization in the region.【Method】 Based on the PSR model,20 evaluation index structures were selected from the pressure,state and response criterion layers to construct an ecological security evaluation index system,and the weight of each index was calculated by the entropy weight method,the ecological security index of the Weihe River Basin in 2005,2010,2015 and 2020 was calculated by the comprehensive index method,and finally the obstacle factor was calculated by the obstacle diagnosis model.【Result】 The average ecological security index of the Gansu section of the Weihe River Basin increased from 0. 425 2 in 2005 to 0. 448 6 in 2020,and the ecological security was at the critical security level,and the overall status of ecological security was improved. The ecological security status of the study area showed the characteristics of high in the northeast and low in the southwest in terms of spatial distribution,and the main obstacles to regional ecological security were economic density,GDP per capita,urbanization rate,effective irrigation area,and afforestation area in the year.【Conclusion】 From 2005 to 2020,the ecological security of the Gansu section of the Weihe River Basin showed a better trend,but there were spatial differences,among which the ecological security in the northeast was improved significantly and the ecological security in the western region improved to a small extent.