To effectively resolve the key issues for a dynamic balance between urban land demand and cultivated land resources protection, this study researched the spatio-temporal relationship between urban land and cultivated land change and also revealed the spatio-temporal driving effect of urban land occupying cultivated land. Based on spatial data of urban land and cultivated land in China from 1990 to 2015, as well as comparing the spatio-temporal pattern of urban land and cultivated land in 31 provincial units in the past 25 years, the rate of cultivated land loss occupied by urban land was explicitly measured. To quantitatively depict the spatio-temporal economic benefit and driving mechanism of urban land occupying cultivated land, the Data Envelopment Analysis (DEA) model and geographical detector were also introduced by the study, respectively. The results showed that: 1) in terms of time, urban land area has increased by 2.6×10⁴ km², with a growth rate of 107% and its expansion rate slowed down gradually by 2.4%/5a in 31 provincial units from 1990 to 2015. The cultivated land increased by 1.41×10⁴ km². There was net loss of cultivated land area after 2000, but the rate of loss gradually decreased with 0.21%/5a. New urban land occupied 2.12×10⁴ km² cultivated land, accounting for 72.5% of the total area of new urban land, but the rate of cultivated land area occupied by urban land was decreasing with 0.23%/5a after 2000. 2) Spatially, the expansion area of urban land was gradually decreasing from east to west in China, and the expansion speed of the western region is increasing. The cultivated land area increased in northwest and northeast China, while the loss in the east and central China was serious. The occupying cultivated land by urban land gradually weakened from the east to the west, and the loss of cultivated land area, as well as the seriously occupying cultivated land by new urban land, were mainly distributed in traditional farming areas and coastal areas in China. The output effect of cultivated land occupied by urban land showed a decreasing trend from 1990 to 2015. The provincial units whose output effect value exceeded 0.8 were mainly distributed in coastal areas, while the output effect of northwest areas was generally low. In the same period, the economic development factor was the main driving factor for the occupation of cultivated land by new urban land in China, followed by resource environment factor and policy measures. The driving force of resource environment and economic development factors showed a downward trend as a whole, and the driving force of policy measures was increasing.