[Objective] The spatiotemporal evolution and driving factors of county-level cultivated land use transition were explored in order to provide a scientific basis for sustainable regional agriculture and the coordinated development of the county scale economy, society and ecology. [Methods] Taking each township in Tongwei County, Dingxi City, Gansu Province, on Longzhong Loess Plateau as the research unit, the “spatial-functional” morphology analysis framework, entropy weight method, spatial autocorrelation analysis, and geodetector were used to analyze the spatiotemporal dynamic characteristics and driving factors of cultivated land use transition in Tongwei County from 2005 to 2022. [Results] ① During the study period, the cultivated land use transition index in Tongwei County showed an overall upward trend, with significant growth from 2008 to 2013 and a peak in 2013(0.389). The spatial morphology transition index of cultivated land use increased from 0.130 in 2005 to 0.147 in 2022, and the improvement areas were mainly distributed in the southwestern and northern parts. The functional morphology transition index increased significantly from 0.082 in 2005 to 0.133 in 2022, and differences among townships gradually decreased.② During the study period, the global spatial autocorrelation of regional cultivated land use transition was not significant, and the overall spatial distribution was relatively random. Spatial morphology transition showed a significant positive correlation, with a stable distribution trend of higher values in the east and lower values in the west. Functional morphology transition showed a variation trend of clustering in the south and spreading in the northeast.③ Natural factors were the fundamental influencing factors of regional cultivated land use transition, while policy factors such as socioeconomic development and land remediation projects played a significant promoting role. Cultivated land use transition was jointly driven by two-factor enhancement and nonlinear enhancement effects of the influencing factors of spatial and functional morphology transition. [Conclusion] In the future, the sustainability of cultivated land use transition should be promoted from multiple dimensions by improving agricultural production conditions, strengthening village collective economic organizations, and enhancing farmers' awareness of cultivated land protection.