A semiconductor device structure is provided. The semiconductor device structure includes a substrate, a first fin structure and a second fin structure disposed over the substrate. The semiconductor device structure includes a first gate stack overlapping the first fin structure. The first gate stack has a first width. The first gate stack includes a first work function layer. A first top surface of the first work function layer is positioned above the first fin structure by a first distance. The semiconductor device structure includes a second gate stack disposed overlapping the second fin structure. The first width is less than a second width of the second gate stack. A second top surface of a second work function layer of the second gate stack is positioned above the second fin structure by a second distance. The first distance is less than the second distance.