[Objective] The ecological security of cultivated land in the lower reaches of the Yellow River was dynamically evaluated to diagnose the factors of man-made obstacles, in order to discover the harm caused by unreasonable human behaviors to the ecological security of cultivated land and provide realistic scientific basis for ecological protection and high-quality development of the lower reaches of the Yellow River.[Methods] The cultivated land ecological security evaluation index system was established based on PSR model in 49 counties along the lower reaches of the Yellow River, and matter-element extension and Markov chain model were used in the analysis.[Results] ① From 2000 to 2018, the ecological security level of cultivated land in counties along the lower reaches of the Yellow River showed an overall upward trend, from level Ⅳ to level Ⅰ, especially after 2010. ② From 2000 to 2018, the cultivated land ecological security level of each county and district had a transition from unstable to stable, showing a spatial transition from higher in the northeast and lower in the central and western regions to higher in the northeast-southwest and lower in the central region, and the spatial differences continued to shrink. ③ Per capita arable land area, population density, and the amount of chemical fertilizer used per arable land area were the main human obstacles affecting the ecological security of cultivated land in the lower reaches of the Yellow River.[Conclusion] During the study period, the ecological security level of cultivated land along the lower reaches of the Yellow River showed an upward trend, and the spatial difference of cultivated land ecological security level in each county continued to narrow, which was greatly affected by human activities. In the future, we should promote the improvement of cultivated land ecological security level in the Yellow River basin from three aspects:expanding new agricultural management subjects, implementing geese returning project and constructing intelligent cultivated land platform.