The expansion of built-up areas has a significant impact on the spatial distribution of land use within a given region. The accurate identification of appropriate regions for the expansion of builtup land holds significant importance in shaping the future distribution of land use patterns. Using Sanmenxia City in Henan Province as a case study, this analysis focuses on obstacle factors such as the suitability of land resources, ecological service value, and ecological security. A built-up land expansion suitability evaluation index system was developed, and the weights were determined using entropy gray correlation analysis. We employed the weighted average comprehensive index model to examine the attributes associated with the suitability of built-up land expansion within the designated study region. Subsequently, the PLUS model was employed to simulate the prospective land utilization within the study area, with the suitability of built-up land expansion as a constraint. The findings of this study will serve as a fundamental framework for informing decision-making processes pertaining to land space planning, ecological construction, and urban development in Sanmenxia City.