Abstract: It is vital to identify the changes in cultivated land quantity and its effect on regional land use structure to understand the urbanization process and regional sustainability. To determine the spatiotemporal evolution characteristics and driving mechanism of the cultivated land quantity, the niche was measured for land use types and six districts in Xiamen City from 1990 to 2015. The results identified by the niche ecostate-ecorole, expansion-compression, breadth, and entropy measurements showed that:1) the cultivated land quantity niche in Xiamen declined gradually from 1990 to 2015, with an average annual compression rate of 1.45%, which was directly related to the expansion of the construction land quantity niche. The evolution of cultivated land quantity niche in Xiamen City was in the late stagnating stage. However, it was faster than that of the national cultivated land niche ecostate-ecorole, possibly due to the rapid urbanization process. 2) The change in cultivated land quantity niche in the six urban districts was consistent with that in Xiamen City, and followed an overall decreasing trend. There was a large difference in the cultivated land area occupancy rate and the decrease rate in cultivated land area in each district. The evolution characteristics of the cultivated land quantity niche in each district could be classified into three distinct categories. First, the breadth of cultivated land quantity niche in the Huli and Siming districts were smaller than that of the construction land. The cultivated land ecostate was small in the six districts and had little interannual change, and the construction land ecostate rose steadily. Second, the breadth of the cultivated land quantity niche in the Jimei and Haicang districts had undergone a change from greater to lower than that of the construction land. The cultivated land ecostate was in the middle of the six districts, and the construction land ecostate increased greatly. Third, the range of change in the breadth of cultivated land and construction land quantity niche was the smallest in the Tong'an and Xiang'an districts. The cultivated land ecostate was at a high level among the six districts, and the construction land ecostate in the Tong'an district showed the largest increase. 3) In the context of rapid urbanization and intensive industrialization, the difference in comprehensive benefit niche between the cultivated land and construction land became gradually wider in Xiamen City, which drove the evolution of the cultivated land quantity niche. Among the difference in benefit niche from economic, ecological, and social aspects, the differences in the economic benefit niche for cultivated land and construction land were the largest, which indicated that the economic benefits were the major benefits for the change in the quantity of cultivated land and construction land. This paper attempted to describe the change in cultivated land quantity in Xiamen City by using the niche theory. This study could improve our understanding of cultivated land protection and the changes in land use structure to support sustainable land resource management.