Abstract: A double-clutch transmission (DCT) includes, but is not limited to an inner input shaft inside an outer input shaft. A first clutch disc and a second clutch disc of the DCT are connected to the two input shafts respectively. Pinions are fixed onto three parallel layshafts of the DCT respectively. The gearwheels on the layshafts include, but are not limited to seven gearwheel groups. Each of the gearwheel group includes, but is not limited to a fixed gearwheel that meshes with an idler gearwheel. A fourth fixed gearwheel on the outer input shaft meshes with the fourth gear idler gearwheel and the sixth gear idler gearwheel. In particular, a fifth fixed gearwheel on the inner input shaft meshes with a fifth gear idler gearwheel and the seventh gear idler gearwheel. The gearwheels further includes, but is not limited to a reverse gearwheel group that includes, but is not limited to a fixed gearwheel on one of the input shafts, meshing with a reverse gear idler gearwheelon one of the layshafts.