Abstract: Cultivated land ecological security is of great significance to regional ecological environment protection and sustainable development of agricultural economy. Based on the PSR model, this paper constructed an index system, used the panel data of the five provinces and regions in the upper reaches of the Yellow River from 2012 to 2022, used the entropy weight-TOPSIS model to measure the level of cultivated land ecological security in the upper reaches of the Yellow River, and used the obstacle degree model to diagnose the obstacle factors from the criterion layer and the indicator layer respectively. The results showed that, although the level of cultivated land ecological security in the upper reaches of the Yellow River was generally low, it had been continuously improved in recent years. The ecological security index of cultivated land in the upper reaches of the Yellow River increased from 0.406 to 0.457 in 2012-2022. Its regional differences were obvious, showing an unbalanced and uneven evolution trend during the study period. From the analysis of criterion layer, the obstacle degree of pressure and response layer was small, and the ecological security of cultivated land was mainly affected by the state. From the index layer analysis, per capita grain occupancy, natural population growth rate, soil erosion control area, multiple cropping index, grain yield per unit area were the main obstacle factors affecting the ecological security of cultivated land in the upper reaches of the Yellow River. It could be seen that the ecological security of cultivated land in the upper reaches of the Yellow River had improved, but the level was still low, so it was necessary to take measures to protect cultivated land according to local conditions.