Objective This study aims to clarify the spatiotemporal evolution patterns， obstacle factors， and cultivated land improvement zoning in the Loess Plateau of northern Shaanxi from 1990 to 2020， and to optimize the regional allocation of cultivated land resources and achieve the strategy of "grain security in the land". Methods Taking Yulin City as the study area， the evaluation indicator system for cultivated land quality mainly covered five aspects： climatic conditions， soil nutrients， cultivated land management， site conditions， and physicochemical properties. The spatial autocorrelation model and the obstacle degree model were introduced to analyze the spatiotemporal evolution characteristics and core restrictive factors of cultivated land quality， and based on this， the improvement zones were scientifically delineated. Results 1） From 1990 to 2020， the cultivated land quality index in Yulin City showed an upward trend （rising from 0.52 to 0.55）， with a spatial distribution pattern of "higher in the east and lower in the west， and higher in the south and lower in the north". 2） The spatial heterogeneity was significant. The high-high-clustering-type cultivated land was distributed in Suide County， Wubu County， and other loess hilly-gully regions， while low-low-clustering-type cultivated land was concentrated in Dingbian County， Jingbian County， and other sandy grassland areas. 3） The diagnosis of obstacle factors indicated that accumulated temperature was the primary factor restricting cultivated land quality in Yulin City. Based on the dominant obstacle factor types， the city was divided into 22 regional types， including accumulated temperature zone， average patch area-pH zone， and organic carbon zone， with differentiated improvement plans proposed for key zones. Conclusion The research findings can provide a scientific basis for cultivated land quality protection and high-quality agricultural development in the northern Shaanxi Loess Plateau.